Primary mesenteric malignant mixed mesodermal (Mullerian) tumor with neuroendocrine differentiation

Extragenital malignant mixed mesodermal (mullerian) tumors (MMMT) are rare neoplasms, with but 24 well documented cases in the literature. Neuroendocr ine differentiation in mixed mullerian neoplasms has been mentioned only an ecdotally, We report on the clinical, pathological, and immunohistochemical features of a hitherto-undescribed extragenital MMMT with prominent neuroe ndocrine differentiation arising from the jejunal mesentery, This lesion wa s composed of a poorly differentiated epithelial component and a spindle ce ll component with heterologous (rhabdomyoblastic) differentiation. The bulk of the tumor consisted of small cell neuroendocrine carcinoma, which exhib ited strong immunoreactivity for NSE, LEU-7, chromogranin A and synaptophys in. Electronmicroscopy confirmed the presence of neurosecretory dense-core granules. The primary mesenteric origin of the tumor was established at aut opsy. Along with a brief review of previously reported extragenital MMMT so me histogenetic concepts relevant to this case are discussed.