Histiocytic sarcoma of the parotid gland region.

Histiocytic sarcoma (HS) is a malignant neoplasm showing the morphological and immunophenotypic features of mature histiocytes. Reported herein is a case of HS of the parotid gland region. A 53-year-old woman noticed a swelling of the right preauricular area. Preoperative fine needle aspiration cytology showed an admixture of pleomorphic atypical cells and mature lymphocytes. She underwent total parotidectomy. Grossly, the tumor was located at the parotid gland to subcutaneous tissue, and showed infiltrative growth with massive necrosis and hemorrhage. Microscopically, the tumor was composed of marked pleomorphic cells with eosinophilic cytoplasm. Bizarre multinuclear giant cells were scattered and intermingled. Tumor cells were positive for CD68 (KP-1 and PG-M1), CD163, S-100 protein, CD1a, CD4 and CD31, but negative for CD3, CD20, CD21, CD79a, DEC205 and langerin, immunohistochemically. Monoclonal proliferation of B cells was not confirmed on polymerase chain reaction for IgH. The patient had recurrent lesions in the pelvis and stomach 5 months after parotidectomy and died of the disease 10 months after the operation.