[469] The Role of Immunohistochemical Markers in the Distinction of Epithelioid and Spindle Cell Tumors of the Skin: A Clinicopathological and Immunohistochemical Study.

J Noelle Buonaccorsi, Samuel T Hwang, Saul Suster, Jose A Plaza. Medical College of Wisconsin, Milwaukee

Background: Cutaneous epithelioid and spindle cell neoplasms occasionally pose a significant diagnostic challenge on purely histologic grounds alone. Given the substantial clinicopathologic overlap between these lesions, especially in small biopsies, the use of immunohistochemical (IHC) studies are essential. Conflicting reports exist about the degree of sensitivity of P63 and CD10 expression in carcinomas and atypical fibroxanthomas (AFX). Cytokeratin reactivity has been categorized as a sensitive marker for epithelial neoplasms; however, in poorly differentiated carcinomas its expression can be focal or even absent. In addition, tumors with different lineages of differentiation, such as leiomyosarcoma, may show focal expression of cytokeratin as well. The purpose of this study was to investigate the utility of a battery of IHC markers including podoplanin (D2-40), CD10, P63, SMA and cytokeratin, in distinguishing cutaneous epithelioid and spindle cell tumors.
Design: A total of 51 epithelioid and spindle cell tumors of the skin form the basis of our study, including 13 AFX, 13 spindle cell melanomas, 9 leiomyosarcomas, 7 leiomyomas, 6 angioleiomyomas and 3 sarcomatoid carcinomas. The antibodies employed were podoplanin, CD10, P63, wide spectrum cytokeratin and SMA. Appropriate positive and negative controls were run concurrently for the markers tested.
Results: IHC results are as follows- AFX: CD10 (11/13), P63 (0/13), CK (1/13), SMA (6/13), Podoplanin (6/13). Spindle cell melanoma: CD10 (8/13), P63 (0/13), CK (0/13), SMA (5/13), Podoplanin (2/13). Leiomyosarcoma: CD10 (4/9), P63 (0/9), CK (2/9), Podoplanin (1/9). Sarcomatoid carcinoma: CD10 (3/3), P63 (3/3), CK (2/3), SMA (3/3), Podoplanin (1/2). One case of leiomyoma was positive for Podoplanin; all other immunostains were negative in both leiomyoma and angioleiomyoma.
Conclusions: In summary, our findings show that the inclusion of certain IHC markers are a useful adjunct in the evaluation of epithelioid and spindle cell tumors of the skin. As opposed to other studies, we found that P63 is a highly sensitive marker for epithelial neoplasms. We also found that CD10 and podoplanin are non-specific markers in cutaneous epithelioid and spindle cell tumors of the skin regardless of their staining pattern. Awareness of this occurrence is extremely important because the prognostic and therapeutic implications of these neoplasms are quite different.
Category: Dermatopathology

Monday, February 28, 2011 1:45 PM

Platform Session: Section F, Monday Afternoon

 

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