[513] SOX10: A Useful Marker for Identifying Metastatic Melanoma in Sentinel Lymph Nodes

Brian C Willis, Jason Wang, Cynthia Cohen. Emory University, Atlanta, GA

Background: SOX10 (Sry-related HMg-Box gene 10) is a key nuclear transcription factor in the differentiation of neural crest progenitor cells to melanocytes. It has been shown to be a sensitive and specific marker of malignant melanoma in multiple tissue types as well as a useful tool in differentiating desmoplastic melanoma from benign dermal scars. Currently, sentinel lymph node biopsy is standard of care in determining treatment strategy and prognosis in cases of known malignant melanoma. The aim of our study was to examine the immunostain profile of SOX10 in sentinel lymph nodes potentially involved by metastatic melanoma, and additionally compare it to current commonly utilized immunostains (S100 protein, HMB-45, and Melan-A).
Design: 77 cases of sentinel lymph nodes diagnosed as positive for metastatic melanoma and 30 cases negative for metastatic melanoma were examined using S100 protein, HMB-45, Melan-A, and SOX10. The four stains were compared for positive staining, intensity of staining, and percentage of cells stained. False positives including inflammatory cell staining and subcapsular nevi were screened for in both positive and negative cases. Cases in which metastases were lost on additional levels were excluded from the comparison.
Results: SOX10 staining showed a statistically significant increase in staining intensity when compared to S100 protein, HMB-45, and Melan-A (p=.000, p= .000, and p=.003 respectively). Additionally, there was a statistically significant increase in percentage of tumor cells stained by SOX10, compared to S100 protein, HMB-45 and Melan-A (p=.015, p=.000, and p=.001 respectively). SOX10 identified metastatic melanoma in all of the cases examined, while the highest number of false negatives was seen in HMB-45 (seven cases, 13%). SOX10 stained background inflammatory cells in two cases, while HMB-45 and Melan-A stained showed similar patterns in three cases.
Conclusions: SOX10 is a useful marker for the identification of metastatic melanoma in sentinel lymph nodes. It consistently identifies metastases in 100% of cases examined, while showing minimal staining of other constituents of normal lymph nodes. Subjectively, interpretation was less ambiguous in the SOX10 stained slides due to the nuclear staining pattern and absence of staining of dendritic cells as seen in S100 protein. We conclude that given the sensitivity and specificity of SOX10 for detecting metastatic melanoma in sentinel lymph nodes, it may play a significant role in supplementing and potentially replacing traditionally utilized immunostains.
Category: Dermatopathology

Monday, March 4, 2013 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 72, Monday Morning

 

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