Pelvic malignant mixed mesodermal tumor of uncertain origin: a case report

Extra-uterine, and especially extragenital, malignant mixed mesodermal tumors (MMMT) are very rare. A large intrapelvic tumor resected from a 56-year-old woman was investigated with morphological and immunohistochemical methods. A large, soft and fragile tumor was located in the pelvic space. The tumor showed high cellularity and was biphasic; it consisted of an admixture of adenocarcinoma and various kinds of sarcomas. The latter were comprised of high-grade endometrial stromal sarcoma, pleomorphic sarcoma, and chondrosarcoma. The pleomorphic sarcoma showed a storiform pattern. The periodic acid-Schiff-positive eosinophilic hyaline droplets and globules in multinucleated giant cells revealed a typical ring-like or peripheral staining for alpha-1-antitrypsin and alpha-1 antichymotrypsin. We considered this case to be pelvic MMMT of uncertain origin, heterologous type.