[A case of intracranial amelanotic melanoma]

Malignant melanoma is usually black in color because of the existence of melanin pigments in it. Differing from such a usual melanoma, amelanotic melanoma, which has no melanin pigments and is not black-colored, is rarely described in literature. In this report, a case of intracranial amelanotic melanoma of unknown origin is presented and discussed. This represents the seventh case report of an intracranial amelanotic melanoma. On May 28, 1984, a 55-year-old man was admitted to our department because of repeated left hemiconvulsion. Neurological and physical examination disclosed left hemiparesis, poor concentration and right inguinal tumors. CT scan revealed a right posterior frontal mass with ring like enhancement. On June 7, the patient underwent craniotomy. The brain tumor, partly emerged from right frontal lobe, was reddish and easy to bleed. Macroscopically there were no abnormal findings over leptomeniges. The right inguial tumors, that were lymph nodes, were also removed simultaneously. Microscopic interpretation at that time was that of a malignant tumor of ectodermal origin. Although no melanin pigments were demonstrated in any specimens except for a part of lymph nodes, dopa reaction was positive in both specimens from the brain tumor and the inguial lymph nodes, strongly suggesting amelanotic melanoma. Postoperative course was uneventful, but CT scan of Aug. 31 again showed multiple intracerebral enhanced lesion and ventricular hemorrhage. Aphasia, right hemiparesis and consciousness disturbance developed gradually, and he died on Sept. 21, 1984. Autopsy demonstrated multiple intracerebral hematomas, containing much tumor cells in lung, thyroid and subcutaneous tissue. Primary lesion remained unknown in spite of an extensive examination in autopsy.(ABSTRACT TRUNCATED AT 250 WORDS)