Oligodendroglioma: HMB-45 positivity using catalyzed signal amplification method - An immunohistochemical (HMB-45, CD31, p53, Mib-1) and ultrastructural study

Although melanin synthesis and the presence of melanosomes are exceptionall y reported in nervous system tumors, there is no record of melanotic oligod endrogliomas in the literature. The purpose of the current study was to eva luate whether melanosomes are immunohistochemically and ultrastructurally d etectable in nonmelanotic oligodendrogliomas and to verify whether these da ta are related to prognosis. Thirty surgical specimens (19 primary lesions and 11 recurrences) from 19 patients were examined. Median survival was 80 months. Immunohistochemical studies were performed using the monoclonal ant ibodies HMB-45, CD31, Mib-1, and p53. Using catalyzed signal amplification (CSA), HMB-45 positivity was noticed in 3 (10%) of the oligodendrogliomas b eings studied. No correlation with survival was found. Ultrastructural exam ination displayed the presence of melanosomelike structures. Tumor vascular ization, estimated by means of CD31 antibody, was increased in 6 of 19 prim ary lesions but there was no significant correlation with survival. Nine of the 19 primary lesions were p53 negative. In these cases, survival was lon ger than in p53-positive tumors (P = 0.0213). Proliferation rate, evaluated with Mib-1, was unrelated to survival, but proved greater in recurrences ( 10 of 11 cases) than in primary tumors (7 of 19 lesions; P = 0.007).