Abstract
We examined clinically and morphologically two primary and two metastatic (from the parotic gland and the lower leg) malignant fibrous histiocytomas (MFH) of the lung. One patient with primary MFH of the lung has survived. The diagnosis was made preoperatively by percutaneous lung biopsy in only one patient. The difinitive diagnosis of MFH is considered to be difficult with a small biopsy specimen because of the diverse histopathology of the tumor.
The histological appearance of primary MFH of the lung differed from that of metastatic MFH; a striform pattern was dominant in the former, while a pleomorphic pattern was dominant in the latter. Metastatic or recurrent lesion were treated with irradiation in three patients, and there was marked shrinking of the lesions in all three. This is because of the histological characteristics of the pleomorphic tumor, and radiotherapy rather than surgery should be considered first for metastatic or recurrent lesions of MFH.
No marked difference was observed in the microstructure of fibroblast-like and histiocyte-like tumor cells. Since the number of the former cells increased with growth of the tumor, MFH is considered to be derived from the histiocyte series.
