Bio

Publications

All Publications


  • PRAME expression in melanocytic proliferations with intermediate histopathologic or spitzoid features. Journal of cutaneous pathology Raghavan, S. S., Wang, J. Y., Kwok, S., Rieger, K. E., Novoa, R. A., Brown, R. A. 2020

    Abstract

    BACKGROUND: PRAME (PReferentially expressed Antigen in MElanoma) has shown utility in distinguishing melanoma from benign melanocytic lesions, but knowledge of its expression pattern in intermediate melanocytic and spitzoid proliferations is limited.METHODS: Immunohistochemical expression of PRAME was examined in 112 melanocytic proliferations with intermediate histopathologic or spitzoid features.RESULTS: Any intensity of PRAME staining in at least 60% of lesional melanocytes was determined as the best threshold for diffuse staining in this cohort. Nearly all non-spitzoid melanomas (23/24; 95.8%) demonstrated diffuse PRAME expression. PRAME was completely negative in 95.6% (43/45) of mitotically-active nevi, traumatized nevi, nevi with persistent/recurrent features, and dysplastic nevi. Most Spitz nevi (15/20) and atypical Spitz tumors (10/13) entirely lacked PRAME expression. One Spitz nevus, one atypical Spitz tumor, and one case of spitzoid melanoma (1/2) demonstrated diffuse PRAME expression.CONCLUSIONS: Although diffuse PRAME expression is generally limited to malignant melanoma, benign Spitz nevi and atypical Spitz tumors can infrequently express diffuse PRAME. PRAME immunohistochemistry can be useful in the evaluation of atypical melanocytic proliferations with intermediate histopathologic features but should be interpreted with caution in the setting of spitzoid neoplasms. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1111/cup.13818

    View details for PubMedID 32700786

  • Diagnostic Utility of LEF1 Immunohistochemistry in Differentiating Deep Penetrating Nevi From Histologic Mimics. The American journal of surgical pathology Raghavan, S. S., Saleem, A., Wang, J. Y., Rieger, K. E., Brown, R. A., Novoa, R. A. 2020

    Abstract

    Deep penetrating nevi (DPNs) are intermediate grade lesions which have the capacity to recur, metastasize, or progress to melanoma. Differentiating DPN from other melanocytic lesions including blue and cellular blue nevi can be diagnostically challenging, and markers to distinguish these entities can be useful. Mutations of the beta-catenin and mitogen-activated protein kinase pathways have recently been elucidated as distinctive of DPN. This pathway can subsequently activate lymphoid enhancer-binding factor 1 (LEF1), a transcription factor shown to facilitate the epithelial-mesenchymal transition to propagate tumorigenesis. Seventy-two cases in total were examined on hematoxylin and eosin sections and with beta-catenin and LEF1 immunohistochemistry. This included: DPN (14), cellular blue nevi (19), blue nevi (15), congenital melanocytic nevi (12), and melanoma (12). Nuclear expression of LEF1, present throughout the entire depth of the lesion, was noted in 13/14 (93%) of DPN, 0/19 (0%) of cellular blue nevi, 0/15 (0%) of blue nevi, 1/12 (8%) of congenital melanocytic nevi, and 9/12 (75%) of melanoma cases. Nuclear expression of beta-catenin, present throughout the entire depth of the lesion, was noted in 14/14 (100%) of DPN, 0/18 (0%) of cellular blue nevi, 0/15 (0%) of blue nevi, 1/12 (8%) of congenital melanocytic nevi, and 1/12 (8%) of melanoma cases. A majority of congenital melanocytic nevi demonstrated a gradient of LEF1 and beta-catenin expression with more intense staining superficially and loss of staining with increasing depth. Deep, uniform nuclear LEF1 combined with beta-catenin immunohistochemical staining can be useful in distinguishing DPN from histologic mimics.

    View details for DOI 10.1097/PAS.0000000000001513

    View details for PubMedID 32520758

  • Molecular profiling of a primary cutaneous signet-ring cell/histiocytoid carcinoma of the eyelid. Journal of cutaneous pathology Raghavan, S., Clark, M., Louie, C., Jensen, K. C., Dietrich, B., Beadle, B. M., El-Sawy, T., Baik, F., Kunder, C. A., Brown, R. A. 2020

    Abstract

    Primary cutaneous signet-ring cell/histiocytoid carcinoma of the eyelid is a rare and aggressive neoplasm. Fewer than 50 cases have been reported in the literature, and the genetic driving mutations are unknown. Herein, we present a case of this rare disease along with the results of molecular profiling via targeted next generation sequencing. The patient is an 85-year-old man who presented with left eyelid swelling initially thought to be a chalazion. After no response to incision and drainage and antibiotics, an incisional biopsy was performed. Histologic sections revealed a proliferation of cells with signet-ring and histiocytoid morphology arranged singly and in cords infiltrating the dermis, subcutaneous tissue, and muscle. The lesional cells strongly expressed cytoplasmic cytokeratin 7 and nuclear androgen receptor. Next generation sequencing revealed a CDH1 mutation, which is known to confer signet-ring morphology in other carcinomas. Pathogenic mutations in NTRK3, CDKN1B and PIK3CA were also detected. To our knowledge, this is the first documented genetic analysis of this rare disease with findings that offer insights into disease pathogenesis and potential therapeutic targets. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1111/cup.13733

    View details for PubMedID 32358805

  • Characterization of Islet of Langerhans Invasion in Pancreatic Ductal Adenocarcinoma Raghavan, S., Lin, C., Longacre, T., Charville, G. NATURE PUBLISHING GROUP. 2020: 1671
  • Mismatch Repair Deficiency and PD-L1 Expression in Sebaceous Carcinomas and Basal Cell Carcinomas with Sebaceous Features. David, B., Raghavan, S., Mills, A. NATURE PUBLISHING GROUP. 2020: 460
  • Gastrointestinal Stromal Tumors Arising in Uncommon Locations: Clinicopathologic Features and Risk Assessment of Esophageal, Appendiceal, and Colonic Tumors Hu, S., Alpert, L., Goldblum, J., Bakhshwin, A., Shetty, S., Graham, R., Wang, H., Lollie, T., Yantiss, R., Hissong, E., Siddique, A., Resnick, M., Wu, E., Panarelli, N., Kuan, K., Pomper, J., Bellizzi, A., Klimstra, D., Shia, J., Vyas, M., Longacre, T., Raghavan, S., Misdraji, J., Kakar, S., Choi, W., Robert, M., Li, H., Feely, M., Bronner, M., Dong, Z., Hosseini, M., Hu, J., Westerhoff, M., Cheng, J., Cooper, H., Nagarathinam, R., Agostini-Vulaj, D., Gao, Z., Demko, N., Lauwers, G., Ghayouri, M., Hart, J., Gonzalez, R. NATURE PUBLISHING GROUP. 2020: 682?83
  • Smooth muscle tumors of the gastrointestinal tract: an analysis of prognostic features in 407 cases. Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc Alpert, L., Al-Sabti, R., Graham, R. P., Pai, R. K., Gonzalez, R. S., Zhang, X., Smith, V., Wang, H. L., Westbrook, L., Goldblum, J. R., Bakhshwin, A., Shetty, S., Klimstra, D. S., Shia, J., Askan, G., Robert, M. E., Thomas, C., Frankel, W. L., Alsomali, M., Hagen, C., Mostafa, M. E., Feely, M. M., Assarzadegan, N., Misdraji, J., Shih, A. R., Agostini-Vulaj, D., Meis, J. M., Tang, S., Chatterjee, D., Kang, L., Hart, J., Lee, S. M., Smith, T., Yantiss, R. K., Hissong, E. M., Gao, Z., Wu, J., Resnick, M. B., Wu, E. Y., Pai, R. K., Zhao, L., Doyle, L. A., Chopra, S., Panarelli, N. C., Hu, S., Longacre, T. A., Raghavan, S. S., Lauwers, G. Y., Ghayouri, M., Cooper, H. S., Nagarathinam, R., Bellizzi, A. M., Kakar, S., Hosseini, M., Rong, J., Greenson, J. K., Lamps, L. W., Dong, Z., Bronner, M. P. 2020

    Abstract

    Smooth muscle tumors represent the second most common mural mesenchymal neoplasm in the gastrointestinal tract, but established criteria for prognostic assessment of these tumors are lacking. A large cohort of surgically resected intramural gastrointestinal smooth muscle tumors from 31 institutions was analyzed to identify potential prognostic features. Pathologic features were assessed by expert gastrointestinal and/or soft tissue pathologists at each center. Immunohistochemical confirmation was required. A total of 407 cases from the esophagus (n=97, 24%), stomach (n=180, 44%), small bowel (n=74, 18%), and colorectum (n=56, 14%) were identified. Patients ranged in age from 19 to 92 years (mean 55 years), with a slight female predominance (57%). Mean tumor size was 5.4cm, with the largest tumor measuring 29cm. Disease progression following surgery, defined as local recurrence, metastasis, or disease-related death, occurred in 56 patients (14%). Colorectal tumors were most likely to progress, followed by small bowel and gastric tumors. None of the esophageal tumors in this series progressed. Receiver operator characteristic analysis identified optimal cutoffs of 9.8cm and 3 mitoses/5mm2 for discriminating between progressive and non-progressive tumors. Histologic features strongly associated with progression by univariate analysis included moderate-to-severe atypia, high cellularity, abnormal differentiation (defined as differentiation not closely resembling that of normal smooth muscle), tumor necrosis, mucosal ulceration, lamina propria involvement, and serosal involvement (P<0.0001 for all features). Age, sex, and margin status were not significantly associated with progression (P=0.23, 0.82, and 0.07, respectively). A risk assessment table was created based on tumor site, size, and mitotic count, and Kaplan-Meier plots of progression-free survival for each subgroup revealed progression-based tiers. Based on our findings, it appears that nonesophageal gastrointestinal smooth muscle tumors measuring >10cm and/or showing ?3 mitoses/5mm2 may behave aggressively, and therefore close clinical follow-up is recommended in these cases.

    View details for DOI 10.1038/s41379-020-0492-5

    View details for PubMedID 32051556

  • Spitz melanoma is a distinct subset of spitzoid melanoma. Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc Raghavan, S. S., Peternel, S., Mully, T. W., North, J. P., Pincus, L. B., LeBoit, P. E., McCalmont, T. H., Bastian, B. C., Yeh, I. 2020

    Abstract

    Melanomas that have histopathologic features that overlap with those of Spitz nevus are referred to as spitzoid melanomas. However, the diagnostic concept is used inconsistently and genomic analyses suggest it is a heterogeneous category. Spitz tumors, the spectrum of melanocytic neoplasms extending from Spitz nevi to their malignant counterpart Spitz melanoma, are defined in the 2018 WHO classification of skin tumors by the presence of specific genetic alterations, such as kinase fusions or HRAS mutations. It is unclear what fraction of "spitzoid melanomas" defined solely by their histopathologic features belong to the category of Spitz melanoma or to other melanoma subtypes. We assembled a cohort of 25 spitzoid melanomas diagnosed at a single institution over an 8-year period and performed high-coverage DNA sequencing of 480 cancer related genes. Transcriptome wide RNA sequencing was performed for select cases. Only nine cases (36%) had genetic alterations characteristic of Spitz melanoma, including HRAS mutation or fusion involving BRAF, ALK, NTRK1, or MAP3K8. The remaining cases were divided into those with an MAPK activating mutation and those without an MAPK activating mutation. Both Spitz melanoma and spitzoid melanomas in which an MAPK-activating mutation could not be identified tended to occur in younger patients on skin with little solar elastosis, infrequently harbored TERT promoter mutations, and had a lower burden of pathogenic mutations than spitzoid melanomas with non-Spitz MAPK-activating mutations. The MAPK-activating mutations identified affected non-V600 residues of BRAF as well as NRAS, MAP2K1/2, NF1, and KIT, while BRAF V600 mutations, the most common mutations in melanomas of the WHO low-CSD category, were entirely absent. While the "spitzoid melanomas" comprising our cohort were enriched for bona fide Spitz melanomas, the majority of melanomas fell outside of the genetically defined category of Spitz melanomas, indicating that histomorphology is an unreliable predictor of Spitz lineage.

    View details for DOI 10.1038/s41379-019-0445-z

    View details for PubMedID 31900433

  • DDIT3 Immunohistochemistry Is a Useful Tool for the Diagnosis of Myxoid Liposarcoma. The American journal of surgical pathology Scapa, J. V., Cloutier, J. M., Raghavan, S. S., Peters-Schulze, G., Varma, S., Charville, G. W. 2020

    Abstract

    Myxoid liposarcoma is a malignant adipogenic neoplasm characterized by prominent arborizing capillaries, occasional lipoblasts, and primitive-appearing spindle cells in a myxoid background. A recurrent translocation in myxoid liposarcoma results in an oncoprotein consisting of full-length DDIT3 (CHOP) fused to an N-terminal segment of either FUS (TLS) or, less often, EWSR1. Here, we explore the diagnostic significance of DDIT3 expression in myxoid liposarcoma using a mouse monoclonal antibody recognizing an epitope in the N-terminal region. Studying a total of 300 tumors, we find diffuse, moderate-to-strong nuclear-localized anti-DDIT3 immunoreactivity in all 46 cases of myxoid liposarcoma representing 36 unique tumors, including 6 cases with high-grade (round cell) morphology. DDIT3 immunohistochemistry also highlighted a distinctive vasculocentric growth pattern in 7 myxoid liposarcomas treated with neoadjuvant radiation. In contrast, the vast majority of other examined lipomatous and myxoid neoplasms exhibited no DDIT3 expression; limited, weak immunoreactivity in <10% of cells was infrequently observed in dedifferentiated liposarcoma (6/39, 15%), solitary fibrous tumor (3/12, 25%), pleomorphic liposarcoma (1/15, 7%), and high-grade myxofibrosarcoma (2/17, 12%). Although this minimal DDIT3 expression did not correlate with DDIT3 amplification or myxoid liposarcoma-like morphology in dedifferentiated liposarcoma, there was evidence among sarcomas (excluding myxoid liposarcoma) of a relationship between expression and exposure to neoadjuvant radiation or cytotoxic chemotherapy. The constellation of findings indicates that DDIT3 immunohistochemistry may have utility in the evaluation of myxoid and lipomatous neoplasms to support the diagnosis of myxoid liposarcoma.

    View details for DOI 10.1097/PAS.0000000000001564

    View details for PubMedID 32815829

  • Diffuse PRAME expression is highly specific for malignant melanoma in the distinction from clear cell sarcoma. Journal of cutaneous pathology Raghavan, S. S., Wang, J. Y., Toland, A., Bangs, C. D., Rieger, K. E., Novoa, R. A., Charville, G. W., Brown, R. A. 2020

    View details for DOI 10.1111/cup.13812

    View details for PubMedID 32681554

  • CLINICOPATHOLOGICAL FEATURES OF NONALCOHOLIC STEATOHEPATITIS (NASH)-RELATED HEPATOCELLULAR CARCINOMA (HCC) Arjunan, V., Prabhakar, V., Raghavan, S., Tulu, Z., Kambham, N., Ahmed, A., Kwo, P., Dhanasekaran, R. WILEY. 2019: 548A
  • IS IT GOOD IDEA TO OFFER TRANSPLANT EXCEPTION POINTS FOR SEPTUAGENARIANS WITH HEPATOCELLULAR CARCINOMA (HCC)? Arjunan, V., Prabhakar, V., Raghavan, S., Tulu, Z., Kambham, N., Ahmed, A., Kwo, P., Dhanasekaran, R. WILEY. 2019: 557A?558A
  • Fragility of Life: Recurrent Intestinal Perforation Due to Vascular Ehlers-Danlos Syndrome DIGESTIVE DISEASES AND SCIENCES Sceats, L. A., Sukerkar, P. A., Raghavan, S. S., Shandiz, A., Shelton, A., Kin, C. 2019; 64 (8): 2120?23
  • A Patient with Sjogren's Syndrome and Subsequent Diagnosis of Inclusion Body Myositis and Light-Chain Amyloidosis JOURNAL OF GENERAL INTERNAL MEDICINE Hom, J., Marwaha, S., Postolova, A., Kittle, J., Vasquez, R., Davidson, J., Kohler, J., Dries, A., Fernandez-Betancourt, L., Majcherska, M., Dearlove, J., Raghavan, S., Vogel, H., Bernstein, J. A., Fisher, P., Ashley, E., Sampson, J., Wheeler, M., Undiagnosed Dis Network 2019; 34 (6): 1058?62
  • Immediate intraoperative sentinel lymph node analysis by frozen section is predictive of lymph node metastasis in endometrial cancer. Journal of robotic surgery Renz, M., Marjon, N., Devereaux, K., Raghavan, S., Folkins, A. K., Karam, A. 2019

    Abstract

    Sentinel lymph nodes sampling (SLN) in endometrial cancer is being evaluated as a means to gather prognostic information about lymphatic metastasis while avoiding the morbidity associated with complete lymphadenectomy. SLN ultrastaging has been advocated to identify low-volume metastases, but its value remains uncertain. This study aims to evaluate a pathological protocol for the immediate intraoperative SLN work-up using H&E staining alone. In this retrospective single-center study, patients received standardized cervical injection of indocyanine green, SLN mapping followed by pelvic lymphadenectomy with or without para-aortic lymphadenectomy. SLNs were entirely frozen, multiple H&E stained sections prepared and evaluated intraoperatively. No immunohistochemistry was performed. SLN results were compared with the complete lymphadenectomy specimen. Over 3.5 years, 90 patients were identified who underwent SLN mapping and subsequent complete pelvic lymphadenectomy. At least one SLN was detected in 79 (88%) patients. The median number of SLNs removed was 2.0. Para-aortic SLNs were detected in 7%. Final pathology showed 67% Type I tumors, 76% locally confined. The mean number of lymph nodes removed during complete lymphadenectomy was 21. In this series, only 6 patients had lymph node metastases. 5/6 were identified by the described SLN approach resulting in 83.3% sensitivity and a negative predictive value of 98.7%. Our approach permits immediate intraoperative results and helps guide the primary surgery. The immediate SLN work-up using frozen sections showed both high accuracy and negative predictive value. The comparably lower sensitivity may be related to the low number of patients with positive lymph nodes (7.6%).

    View details for PubMedID 30687881

  • OLIG2 is a marker of the fusion protein-driven neurodevelopmental transcriptional signature in alveolar rhabdomyosarcoma. Human pathology Raghavan, S. S., Mooney, K. L., Folpe, A. L., Charville, G. W. 2019

    Abstract

    Alveolar rhabdomyosarcoma (RMS) is associated with an underlying pathogenic translocation involving either PAX3 or PAX7 and FOXO1. The presence or absence of this fusion defines the biology and clinical behavior of this subtype of RMS and its identification in tumors is relevant to prognostication and treatment planning. To further explore the unique characteristics of fusion-driven RMS, we leveraged a published gene expression data set to perform an unbiased comparison of 33 fusion-positive and 25 fusion-negative RMS cases. Our analyses revealed 1790 expressed loci with more than two-fold differential expression at a threshold of P<.05. Genes with increased expression in fusion-positive relative to fusion-negative RMS were significantly enriched for those involved in "nervous system development," "neuron differentiation," and "neurogenesis," highlighting a neurodevelopmental gene expression signature driven by the alveolar RMS-associated fusion protein. We show that neurodevelopmental genes are enriched near PAX3-FOXO1 fusion protein binding sites, suggesting a genome-wide fusion protein-mediated activation of cis regulatory elements. Among the genes with differential expression in fusion-positive versus fusion-negative RMS, we identified expression of the transcriptional regulator of motor neuron and oligodendrocyte development, OLIG2, as a marker of the fusion protein-dependent neurodevelopmental signature. Immunohistochemical analysis of a cohort of 73 RMS specimens revealed OLIG2 expression in 96.4% of fusion-positive RMS (N=27/28), but only in 6.7% of fusion-negative RMS (N=3/45; P<.001). The proportion of OLIG2-expressing cells in fusion-negative cases did not exceed 5%, while 92.9% of fusion-positive cases showed expression in at least 5% of cells. Our findings identify OLIG2 expression as a unique manifestation of a neurodevelopmental gene expression signature driven by the oncogenic fusion protein characteristic of alveolar RMS, which may aid in the diagnostic and prognostic distinction of fusion-positive cases.

    View details for DOI 10.1016/j.humpath.2019.07.003

    View details for PubMedID 31299267

  • Fragility of Life: Recurrent Intestinal Perforation Due to Vascular Ehlers-Danlos Syndrome. Digestive diseases and sciences Sceats, L. A., Sukerkar, P. A., Raghavan, S. S., Esmaeili Shandiz, A., Shelton, A., Kin, C. 2019

    View details for PubMedID 30656563

  • A Patient with Sjogren's Syndrome and Subsequent Diagnosis of Inclusion Body Myositis and Light-Chain Amyloidosis. Journal of general internal medicine Hom, J., Marwaha, S., Postolova, A., Kittle, J., Vasquez, R., Davidson, J., Kohler, J., Dries, A., Fernandez-Betancourt, L., Majcherska, M., Dearlove, J., Raghavan, S., Vogel, H., Bernstein, J. A., Fisher, P., Ashley, E., Sampson, J., Wheeler, M. 2019

    Abstract

    We discuss a challenging case of a 58-year-old Vietnamese-American woman who presented to her new primary care provider with an 8-year history of slowly progressive dysphagia, hoarseness, muscle weakness with associated frequent falls, and weight loss. She eventually reported dry eyes and dry mouth, and she was diagnosed with Sjogren's syndrome. Subsequently, she was additionally diagnosed with inclusion body myositis and gastric light-chain (AL) amyloidosis. Although inclusion body myositis has been previously associated with Sjogren's syndrome, inclusion body myositis is rare in non-Caucasians, and the trio of Sjogren's syndrome, inclusion body myositis, and AL amyloidosis has not been previously reported. Sjogren's syndrome is a systemic autoimmune condition characterized by ocular and oral dryness. It is one of the most common rheumatologic disorders in the USA and worldwide. Early diagnosis of Sjogren's is particularly important given the frequency and variety of associated autoimmune diseases and extraglandular manifestations. Furthermore, although inclusion body myositis has a low prevalence, it is the most common inflammatory myopathy in older adults and is unfortunately associated with long delays in diagnosis, so knowledge of this disorder is also crucial for practicing internists.

    View details for PubMedID 30887439

  • Utility of CD30, Ki-67, and p53 in assisting with the diagnosis of mycosis fungoides with large cell transformation JOURNAL OF CUTANEOUS PATHOLOGY Raghavan, S. S., Hong, E. K., Kim, Y. H., Kim, J. 2019; 46 (1): 33?43

    View details for DOI 10.1111/cup.13375

    View details for Web of Science ID 000453901400005

  • Utility of CD30, Ki-67, and p53 in assisting with the diagnosis of mycosis fungoides with large cell transformation. Journal of cutaneous pathology Raghavan, S. S., Hong, E. K., Kim, Y. H., Kim, J. 2018

    Abstract

    INTRODUCTION: Mycosis fungoides (MF) with large cell transformation (LCT) is an advanced stage of cutaneous lymphoma with a poor prognosis. Identification of LCT is critical and especially challenging when the number of large abnormal lymphocytes is near but below 25%. We propose that Ki-67 and p53 may be useful in making this diagnosis.METHODS: We identified 17 patients with advanced stage (T3 or T4) MF without LCT and 38 patients with a biopsy-confirmed new diagnosis of MF with LCT treated at our institution's cutaneous lymphoma clinic from 2012 to 2016. Seventeen patients underwent 22 biopsies with advanced stage MF (control), and 38 patients with 46 biopsies of MF with LCT were included in this study.RESULTS: The MF cohort had an average CD30 expression of 4%, while the MF-LCT cohort had an average CD30 expression of 22% (P<0.05). The MF cohort had an average Ki-67 staining of 13%, while the MF-LCT group had an average Ki-67 staining of 57% (P<0.05). Forty-seven percent of the MF-LCT group was positive for p53; on the other hand, none of the MF control group showed increased p53 expression (P<0.05).DISCUSSION: While CD30 shows some value in delineating large cell transformation, Ki-67 and p53 appear to be useful immunohistochemical markers in the diagnosis of LCT.

    View details for PubMedID 30328119

  • Histopathologic approach to epidermotropic lymphocytic infiltrates SEMINARS IN CUTANEOUS MEDICINE AND SURGERY Raghavan, S. S., Kim, J. 2018; 37 (1): 56?60

    Abstract

    Mycosis fungoides is the most common and therefore quintessential cutaneous lymphoma and is typically characterized by an epidermotropic infiltrate of atypical monoclonal CD4+ lymphocytes. Classical histopathologic findings include epidermotropism, lymphocytes with convoluted nuclear contours and surrounding perinuclear "halos," and papillary dermal fibrosis. Atypical lymphocytes may occasionally form Pautrier's microabscesses with tagging of lymphocytes along the basal keratinocytes. Unfortunately, a variety of benign inflammatory infiltrates, as well as other cutaneous lymphomas, may demonstrate some similar histopathologic findings. Herein, we review the wide array of epidermotropic T-cell lymphomas and discuss distinguishing features between these entities. We also offer an algorithmic approach utilizing histopathologic, immunophenotypic, and molecular techniques that can be used for analyzing an epidermotropic T-cell infiltrate in order to render a specific diagnosis.

    View details for PubMedID 29719021

  • Flexor Tendon Sheath Engineering Using Decellularized Porcine Pericardium. Plastic and reconstructive surgery Megerle, K., Woon, C., Kraus, A., Raghavan, S., Pham, H., Chang, J. 2016; 138 (4): 630e-41e

    Abstract

    The flexor tendon sheath is an ideal target for tissue engineering because it is difficult to reconstruct by conventional surgical methods. The authors hypothesized that decellularized porcine pericardium can be used as a scaffold for engineering a biologically active tendon sheath.The authors' protocol removed cellular material from the pericardium and preserved the structural architecture in addition to the collagen and glycosaminoglycan content. The scaffold was successfully reseeded with human sheath synoviocytes and human adipose-derived stem cells. Cells were evaluated for 8 weeks after reseeding.The reseeded construct demonstrated continuous production of hyaluronic acid, the main component of synovial fluid. After being seeded on the membrane, adipose-derived stem cells demonstrated down-regulation of collagen I and III and up-regulation of hyaluronan synthase 2.The results indicate that decellularized porcine pericardium may be a potential scaffold for engineering a biologically active human tendon sheath.

    View details for DOI 10.1097/PRS.0000000000002459

    View details for PubMedID 27673534

  • Co-Culture of Human Adipose-Derived Stem Cells with Tenocytes Increases Proliferation and Induces Differentiation into a Tenogenic Lineage PLASTIC AND RECONSTRUCTIVE SURGERY Kraus, A., Woon, C., Raghavan, S., Megerle, K., Hung Pham, H., Chang, J. 2013; 132 (5): 754E-766E

    Abstract

    Seeding acellularized tendons with cells is an approach for creating tissue-engineered tendon grafts with favorable biomechanical properties. It was the authors' aim to evaluate whether human adipose-derived stem cells could replace tenocytes for scaffold seeding.Adipose-derived stem cells and tenocytes were co-cultured in different ratios (3:1, 1:1, and 1:3) and with three different methods: (1) direct co-culture, (2) tenocyte-conditioned media on adipose-derived stem cells, and (3) an insert system to keep both cell types in the same media without contact. Proliferation, collagen production, and tenogenic marker expression were measured by hematocytometry, immunocytochemistry, enzyme-linked immunosorbent assay, and real-time polymerase chain reaction.Proliferation and collagen production were similar for tenocytes and adipose-derived stem cells alone. Phenotype difference between adipose-derived stem cells and tenocytes was indicated by higher tenascin C and scleraxis expression in tenocytes. Proliferation was increased in direct co-cultures, especially at an adipose-derived stem cells-to-tenocyte ratio of 3:1, and for tenocytes in adipose-derived stem cell-conditioned media. Direct co-culture caused significant up-regulation in tenascin C expression in adipose-derived stem cells (4.0-fold; p<005). In tenocyte-conditioned media, tenascin C expression was up-regulated 2.5-fold (p<0.05). In the insert system, tenascin C expression was up-regulated 2.3-fold (p<0.05).Adipose-derived stem cells are good candidates for tendon tissue engineering because they are similar to tenocytes in proliferation and collagen production. With an optimal ratio of 3:1, they increase proliferation in co-culture and change their phenotype toward a tenogenic direction.

    View details for DOI 10.1097/PRS.0b013e3182a48b46

    View details for PubMedID 24165627

  • Human Flexor Tendon Tissue Engineering: Decellularization of Human Flexor Tendons Reduces Immunogenicity In Vivo TISSUE ENGINEERING PART A Raghavan, S. S., Woon, C. Y., Kraus, A., Megerle, K., Choi, M. S., Pridgen, B. C., Pham, H., Chang, J. 2012; 18 (7-8): 796-805

    Abstract

    In mutilating hand injuries, tissue engineered tendon grafts may provide a reconstructive solution. We have previously described a method to decellularize cadaveric human flexor tendons while preserving mechanical properties and biocompatibility. The purpose of this study is to evaluate the immunogenicity and strength of these grafts when implanted into an immunocompetent rat model.Cadaveric human flexor tendons were divided into two groups. Group 1 was untreated, and Group 2 was decellularized by treatment with sodium dodecyl sulfate (SDS), ethylenediaminetetraacetic acid (EDTA), and peracetic acid (PAA). Both groups were then analyzed for the presence of major histocompatibility complexes by immunohistochemistry (IHC). Pair-matched tendons from each group were then placed into the dorsal subcutaneous tissue and anchored to the spinal ligaments of Wistar rats for 2 or 4 weeks, and harvested. The infiltration of B-cells and macrophages was determined using IHC. The explants where then subjected to mechanical testing to determine the ultimate tensile stress (UTS) and elastic modulus (EM). Statistical analysis was performed using a paired Student's t-test.The decellularization protocol successfully removed cells and MHC-1 complexes. At 2 weeks after implantation, there was increased infiltration of B-cells in Group 1 (untreated) compared with Group 2 (acellular), both in the capsule and tendon substance. There was improved ultimate tensile stress (UTS, 42.7 8.3 vs. 22.8 7.8 MPa, p<0.05) and EM (830.2 206.7 vs. 421.2 171.3 MPa, p<0.05) in tendons that were decellularized. At 4 weeks, there was continued B-cell infiltration in Group 1 (untreated) compared with Group 2 (acellular). There was no appreciable difference in macrophage infiltration at both time points. At 4 weeks Group 2 (acellular) demonstrated persistently greater UTS (40.5 9.1 vs. 14.6 4.2 MPa, p<0.05) and EM (454.05 101.5 vs. 204.6 91.3 MPa, p<0.05) compared with Group 1 (untreated).Human flexor tendons that were decellularized with SDS, EDTA, and PAA resulted in removal of cellular antigens and a decreased immune response when placed into Wistar rats. These grafts showed better mechanical properties at 2 and 4 weeks when compared with control tendons. Decellularization is an important step toward the use of tissue engineered flexor tendons in upper extremity reconstruction.

    View details for DOI 10.1089/ten.tea.2011.0422

    View details for PubMedID 22011137

  • Optimization of Human Tendon Tissue Engineering: Synergistic Effects of Growth Factors for Use in Tendon Scaffold Repopulation PLASTIC AND RECONSTRUCTIVE SURGERY Raghavan, S. S., Woon, C. Y., Kraus, A., Megerle, K., Hung Pham, H., Chang, J. 2012; 129 (2): 479-489

    Abstract

    Tissue-engineered flexor tendon grafts may allow reconstruction of severe tendon losses. One critical factor is the optimization of cell proliferation and reseeding. Use of growth factors--basic fibroblast growth factor (bFGF), insulin-like growth factor (IGF)-1, and platelet-derived growth factor (PDGF)-BB--may improve culture conditions for human fibroblasts, tenocytes, and adipose-derived stem cells and increase repopulation of a tendon scaffold.All cell types were plated at a density of 10,000 cells per well and cultured in F12 media supplemented with varying concentrations of bFGF, IGF-1, and PDGF-BB. After 72 hours, cell proliferation was determined using the CellTiter assay. Human flexor tendon segments were acellularized and reseeded in a cell suspension of 5 10(5) cells/ml. After 5 days, tendon repopulation was determined using the MTS assay and histology. Statistical significance was determined with analysis of variance and a t test.For all cell types, there was enhanced proliferation with growth factors. Among single growth factors, PDGF-BB at 50 ng/ml was the most efficient stimulator of proliferation. With multiple growth factors, the optimal concentration was determined to be 5 ng/ml bFGF, 50 ng/ml IGF-1, and 50 ng/ml PDGF-BB (increase when compared with control: fibroblasts, 2.92-fold; tenocytes, 2.3-fold; and adipose-derived stem cells, 2.4-fold; p < 0.05). Tendons reseeded with this optimal combination of growth factors showed improved reseeding compared with the control group (fibroblasts, 2.01-fold; tenocytes, 1.78-fold; and adipose-derived stem cells, 1.76-fold; p < 0.05).bFGF, IGF-1, and PDGF-BB can be used to improve cellular proliferation and repopulation of an acellularized scaffold. The use of growth factors may be an important step in the tissue engineering of human flexor tendons.

    View details for DOI 10.1097/PRS.0b013e31823aeb94

    View details for PubMedID 22286428

  • Three-Dimensional-Construct Bioreactor Conditioning in Human Tendon Tissue Engineering TISSUE ENGINEERING PART A Woon, C. Y., Kraus, A., Raghavan, S. S., Pridgen, B. C., Megerle, K., Pham, H., Chang, J. 2011; 17 (19-20): 2561-2572

    Abstract

    Human tendon tissue engineering attempts to address the shortage of autologous tendon material arising from mutilating injuries and diseases of the hand and forearm. It is important to maximize the tissue-engineered construct's (TEC's) biomechanical properties to ensure that the construct is in its strongest possible state before reimplantation. In this study, we sought to determine the bioreactor treatment parameters that affect these properties. Using small- and large-chamber three-dimensional-construct bioreactors (SCB and LCB, respectively), we applied cyclic axial load to TECs comprising reseeded human flexor and extensor tendons of the hand. First, small-sample pilot studies using the LCB were performed on matched-paired full-length flexor tendons to establish proof of concept. Next, large-sample studies using the SCB were performed on matched-paired extensor tendon segments to determine how reseeding, load duty cycle, load magnitude, conditioning duration, and testing delay affected ultimate tensile stress (UTS) and elastic modulus (EM). We found that compared with reseeded matched-paired controls under dynamic-loading at 1.25?N per TEC for 5 days, (1) acellular TECs had lower UTS (p=0.04) and EM (p<0.01), (2) unloaded TECs had lower UTS (p=0.01) and EM (p=0.02), (3) static-loaded TECs had lower UTS (p=0.01) and EM (p<0.01), (4) TECs conditioned for 3 days had lower UTS (p=0.03) and EM (p=0.04), and (5) TECs conditioned for 8 days had higher UTS (p=0.04) and EM (p=0.01). However, TECs conditioned at higher loads (2.5?N per TEC) and lower loads (0.625?N per TEC) possessed similar UTS (p=0.83 and p=0.89, respectively) and EM (p=0.48 and p=0.89, respectively) as controls stimulated with 1.25?N per TEC. After cycle completion, there is attrition of UTS (p=0.03) and EM (p=0.04) over a 2-day period. Our study showed that the material properties of human allograft TECs can be enhanced by reseeding and dynamic-conditioning. While conditioning duration has a significant effect on material properties, the load magnitude does not. The issue of attrition in biomechanical properties with time following cycle completion must be addressed before bioreactor preconditioning can be successfully introduced as a step in the processing of these constructs for clinical application.

    View details for DOI 10.1089/ten.tea.2010.0701

    View details for PubMedID 21612572

  • The utility of endovascular simulation to improve technical performance and stimulate continued interest of preclinical medical students in vascular surgery. Journal of surgical education Lee, J. T., Qiu, M., Teshome, M., Raghavan, S. S., Tedesco, M. M., Dalman, R. L. 2009; 66 (6): 367-373

    Abstract

    New training paradigms in vascular surgery allow for early specialization out of medical school. Surgical simulation has emerged as an educational tool for trainees to practice procedures in a controlled environment allowing interested medical students to perform procedures without compromising patient safety. The purpose of this study is to assess the ability of a simulation-based curriculum to improve the technical performance and interest level of medical students in vascular surgery.Prospective observational cohort study of medical student performance.Academic medical center.Forty-one medical students (23 first year, 15 second year, 3 other) enrolled in a vascular surgery elective course. Students completed a survey of their interests and performed a renal stent procedure on an endovascular simulator (pretest). The curriculum consisted of didactic teaching and weekly mentored simulator sessions and concluded with a final renal stent procedure on the simulator (posttest). Objective procedural measures were determined during the pre- and posttest by the simulator, and subjective performance was graded by expert observers utilizing a structured global assessment scale. After the course, the students were surveyed as to their opinions about vascular surgery as a career option. Finally, 1 year after the course, all students were again surveyed to determine continued interest in vascular surgery.The objective and subjective criteria measured on the simulator and structured global assessment scale significantly improved from pre- to posttest in terms of performer technical skill, patient safety measures, and structured global assessments. Before beginning the course, 8.5% of the students expressed high interest in vascular surgery, and after completing the course 70% were seriously considering vascular surgery as a career option (p = 0.0001). More than 95% of the students responded that endovascular simulation increased their knowledge and interest in vascular surgery. In the 1-year follow-up survey (n = 23 medical students), 35% had already entered their clinical years. Seventy percent of the students were still considering vascular surgery, while several other career options were still popular including the surgical subspecialties (70%), interventional cardiology (57%), and interventional radiology (48%). Most respondents indicated the major reasons for continued interest in vascular surgery were the ability to practice endovascular procedures on the simulator (100%) and mentorship from vascular surgery faculty (78%).The use of high fidelity endovascular simulation within an introductory vascular surgery course improves medical student performance with respect to technical skill, patient safety parameters, and global performance assessment. Mentored exposure to endovascular procedures on the simulator positively impacts long term medical student attitudes towards vascular surgery. Simulator-based courses may have the potential to be an important component in the assessment and recruitment of medical students for future surgical training programs.

    View details for DOI 10.1016/j.jsurg.2009.06.002

    View details for PubMedID 20142137

  • Major Blood Vessel Reconstruction During Sarcoma Surgery ARCHIVES OF SURGERY Song, T. K., Harris, E. J., Raghavan, S., Norton, J. A. 2009; 144 (9): 817-822

    Abstract

    To evaluate the outcomes of major vessel reconstruction as part of surgery to remove sarcomas.Retrospective review.Tertiary academic medical center.Fourteen patients (10 female) with retroperitoneal or extremity sarcomas and major blood vessel involvement who underwent surgery to remove the tumor and had blood vessel reconstruction between 2003 and 2008. Each patient underwent computed tomography angiography.Early (<30 days) and late (>30 days) operative morbidity and mortality, freedom from disease, and graft patency.Seven patients had retroperitoneal sarcomas and 7, extremity sarcomas. Thirteen tumors were malignant (7 high grade and 6 low grade) and 1, benign (leiomyoma). Seven patients had replacement of artery and vein; 5, artery only; and 2, vein only. In all, 16 arteries were reconstructed (2 common femoral; 5 iliac; 2 superficial femoral; 1 brachial; 1 popliteal; and 2 aorta, one with implantation of both iliac arteries and the other with implantation of the left renal, superior mesenteric, and hepatic arteries). Eight patients (57%) had 9 veins reconstructed (3 external iliac, 3 superficial femoral, 2 vena cava, and 1 popliteal). Primary arterial patency was 58% and primary-assisted patency was 83%. Venous patency was 78%. Local recurrence occurred in 3 patients (21%). Five-year disease-free and overall survival were 52% and 68%, respectively. Limb salvage was achieved in 93%.Involvement of vascular structures is not a contraindication for resection of sarcomas, but appropriate planning is necessary to optimize outcome.

    View details for PubMedID 19797105

  • Relationship Between Hypotension and Distribution of Microemboli on DW-MRI Following Carotid Angioplasty and Stenting 81st Annual Scientific Session of the American-Heart-Association Lee, J. T., Kleinman, J. T., Teshome, M., Raghavan, S., Tedesco, M. M., Lane, B., Zhou, W., Dalman, R. L. LIPPINCOTT WILLIAMS & WILKINS. 2008: S1077?S1077

Footer Links:

Stanford Medicine Resources: