Malignant müllerian mixed tumor (carcinosarcoma) of the fallopian tube: an immunohistochemical study of neoplastic cells.

The patient was a 65-year-old woman who complained of lower abdominal pain. Salpingo-oophorectomy and hysterectomy were performed due to suspicion of ovarian cancer. At surgery a polypoid mass was observed in the fimbria of the left fallopian tube. Histologically, proliferation of undifferentiated neoplastic cells with marked cytological atypia predominated in the tumor. Proliferation of rhabdomyoblastic cells or spindle cells, as well as adenocarcinoma arising from the mucosa of the fallopian tube, was observed. A diagnosis of malignant müllerian mixed tumor (MMMT) was made. CD10 was expressed in adenocarcinoma, undifferentiated, spindle and rhabdomyoblastic cells. Furthermore, rhabdomyoblastic cells were positive for desmin and myoglobin. Undifferentiated and spindle neoplastic cells were focally positive for ASMA and negative for h-caldesmon. Finally, our preliminary report suggests that MMMT of the fallopian tube may contain immature smooth muscle cells or cells with the myofibroblast-like immunohistochemical phenotype in the undifferentiated component.