[A case of metastatic malignant melanoma mimicking pancreatic pseudocyst].

A 74-year-old male was admitted to our hospital complaining of an abdominal mass. Abdominal US and ERCP disclosed a cyst in the pancreas, communicating with a crater in the stomach. Spontaneous rupture of a pancreatic pseudocyst into the stomach was considered. Laparotomy demonstrated an irregular black pancreatic cyst, and histological examination showed atypical spindle shaped cells with brown to black pigmentation, compatible with malignant melanoma. Autopsy confirmed the diagnosis of malignant melanoma involving the pancreas, stomach and other organs. Efforts to elucidate the primary site were unsuccessful, Metastatic melanoma without a primary site is well known and has been reported to occur in from 2.4% to 8.7% of all cases. This case suggests that malignant melanoma must be considered in cases of tumors with various symptoms and multiple metastases without a definite primary site.