Malignant fibrous histiocytoma of the pancreas.

An extremely rare case of malignant fibrous histiocytoma in the pancreas is reported. A 70-year-old man complained of upper abdominal discomfort. A tumor in the head of the pancreas was demonstrated by ultrasonography and computed tomography. The surgical specimen revealed a relatively well demarcated tumor, 9 x 7 x 6.5 cm in size. Microscopically, fibroblastic, histiocytic, and multinucleated giant tumor cells were observed in the myxoid area, but some tumor cells had proliferated in a storiform-pleomorphic pattern. Immunohistochemically, some tumor cells were positive for lysozyme, alpha-1-antitrypsin, alpha-1-antichymotrypsin, and vimentin. Electron microscopically, tumor cells showed a combination of fibroblastic and histiocytic features. The patient is currently well with no evidence of recurrence or metastasis 22 months after operation.