Inflammatory malignant fibrous histiocytoma of the gallbladder: report of a case.

We describe herein a case of inflammatory malignant fibrous histiocytoma (IMFH) of the gallbladder that subsequently metastasized to the ascending colon and later to the stomach. A 70-year-old Japanese man with a palpable mass in the right upper quadrant of the abdomen was referred to our hospital for investigation and treatment. Laboratory data showed severe leukocytosis and elevated serum granulocyte colony-stimulating factor (G-CSF) concentrations. A laparotomy was performed, and the tumor was excised en bloc with the gallbladder and part of the liver bed. Histopathologically, the tumor was composed of ordinary malignant fibrous histiocytoma (MFH) components characterized by pleomorphic tumor cells, bizarre giant cells, and conventional spindle cells in a storiform growth pattern, as well as a xanthogranulomatous component, including inflammatory cells, foamy histiocytes, and plasma cells. Immunohistochemical study revealed that the pleomorphic tumor cells and bizarre giant cells were positive for antibodies against alpha1-antitrypsin and alpha1-antichymotrypsin. The final pathologic diagnosis was IMFH. The tumor cells were diffusely positive for anti-G-CSF monoclonal antibody, and the inflammatory reaction subsided immediately after tumor resection, strongly suggesting that the primary tumor cells produced G-CSF. This patient is still alive with no signs of recurrence more than 3 years after his primary operation, which to our knowledge is the longest survival period ever reported. Therefore, visceral IMFH is manageable in some cases by resecting the primary and isolated metastatic lesions.