Author:

Keywords:

Science & Technology, Life Sciences & Biomedicine, Anatomy & Morphology, Medical Laboratory Technology, Pathology, MIC2, SYNOVIAL SARCOMA, PNET, IMMUNOHISTOCHEMISTRY, CELL-SURFACE ANTIGEN, EWINGS-SARCOMA, TUMORS, CHROMOSOMES, TISSUE, 1116 Medical Physiology, 3202 Clinical sciences

Abstract:

Immunohistochemical demonstration of the MIC2 gene product (CD99) represents a valuable diagnostic tool that makes identification of peripheral primitive neuroectodermal tumors easier. Different commercially available antibodies have been raised that show a high sensitivity along with a specificity that is widely regarded as acceptable although not absolute. MIC2 expression has been reported in lymphoblastic lymphoma, occasionally in several other types of sarcoma, and in some neuroendocrine tumors and ependymomas. The recent personal observation of immunopositivity for MIC2 gene product in some synovial sarcomas that had been difficult to diagnose prompted us to undertake a systematic study of a larger series of 50 synovial sarcomas, of which 62% showed positive immunoreactivity for either 013 (Signet) or 12E7 (Dako MIC2). This is the highest incidence of CD99 positivity reported to date in any type of sarcoma other than the Ewing's/primitive neuroectodermal tumor group. Immunopositivity for CD99 was common in all morphologic subtypes of synovial sarcoma. As poorly differentiated synovial sarcoma may overlap morphologically with primitive neuroectodermal tumor, careful histologic examination along with evaluation of a wider panel of differentiation markers is mandatory to avoid this potential diagnostic pitfall, which has both therapeutic and prognostic implications.