A Resected Case of Malignant Fibrous Histiocytoma of the Parotid Salivary Gland

We report here a resected case of malignant fibrous histiocytoma (MFH) of the parotid salivary gland. Only eleven previous cases of MFH involving the parotid salivary glands have been reported in the Englishlanguage literature. A 48-year-old Japanese man was admitted complaining of a slowly growing but not painful tumor that developed in the right cheek, and under the clinical diagnosis of pleomorphic adenoma of the parotid salivary gland, superficial parotidectomy was performed. Macroscopically, an encapsulated nodular tumor involving the parotid salivary gland was seen in the resected specimen, that measured 3 cm in the largest dimension. The cut surface was hard and rubbery, grayish-white in color and lacked necrotic foci. Microscopically, the tumor consisted of scattered atypical spindled and rounded mononuclear cells with hyperchromatic nuclei, which tended to be arranged in a storiform pattern, and occasionally multi-nucleated bizarre cells. The cells did not involve the parotid salivary gland. Immunohistochemically, the cells were negative for keratin, but stained positive for vimentin and focally for a smooth muscle actin. This tumor was pathologically diagnosed as ordinary MFH of the parotid salivary gland arising from the para-glandular tissue. No recurrence was observed two months after surgery.