Primary dural melanoma: a clinical and morphological study.

This study reviews the literature pertaining to primary meningeal melanoma and reports the clinical and ultrastructural findings in a case where the tumor appeared to be of pachymeningeal (dural) origin. This is clearly a departure from all previously described cases, in which a leptomeningeal (pial-arachnoidal) origin was either defined or assumed. Clinically, this case was remarkable in its rarity, its presentation as a cerebellopontine angle syndrome, and its occurrence in a Negro, a race in which melanomas are uncommon. Ultrastructurally, the tumor did demonstrate the presence of basement membrane abnormalities and numerous endothelial fenestrations. However, it was found to be made up of a homogenous cell population, consisting only of electron-lucent, melanin-laden cells. The mixed cell population noted previously in a primary leptomeningeal melanoma was not found in this tumor. In view of the fact that this patient continues to do well 1 1/2 years after operation, with no evidence of tumor recurrence, it is suggested that a homogenous cell population noted on electron microscopy could indicate a better prognosis. In addition, it may also indicate a pachymeningeal rather than a leptomeningeal origin for the tumor. A plea is made for greater specificity in terminology when describing primary meningeal melanomas and for a concerted effort to distinguish between those of dural and those of leptomeningeal origin.