A case of inflammatory malignant fibrous histiocytoma of the colon.

Primary malignant fibrous histiocytoma seldom occurs in the alimentary tract. This report documents a case in which a 50-year-old man presented with abdominal fullness and anorexia, together with inflammatory reactions such as fever, leukocytosis, an elevated erythrocyte sedimentation rate and positive CRP. Radiologic and endoscopic studies revealed a large mass in the ascending colon. The histology of the resected tumor revealed inflammatory malignant fibrous histiocytoma, a histologic subtype which is rare among not only soft tissue fibrous but also as gastrointestinal histiocytomas. The inflammatory reactions disappeared following resection of the tumor. Although we suspected that the tumor produced granulocyte colony-stimulating factor because of the slightly elevated serum level and the characteristics of the tumor histology, an immunohistochemical study failed to show the G-CSF production by the tumor cells.