These tumors may be detected prenatally by ultrasound and MRI. Additionally, preoperative fine needle aspiration can be used to diagnose the tumor. Ancillary testing A phosphotungstic acid hematoxylin stain may be used to highlight cross striations in the cytoplasm of the tumor cells. PAS with diastase will highlight the presence of glycogen in the tumor cells' cytoplasm. Immunohistochemistry will yield a positive reaction with a variety of myoid markers, including desmin, myoglobin, myogenin, MYOD1 and muscle specific actin. They may also be positive with vimentin, smooth muscle actin, and Leu-7. However, the tumor cells are almost always negative with glial fibrillary acidic protein, S100 protein, cytokeratin, epithelial membrane antigen, CD68, FLI1, CD99 and CD56. Although not used as frequently now, electron microscopy will show thick and thin myofilaments, Z-bands: these are features of sarcometric differentiation. Differential diagnosis The differential diagnosis histologically includes<unk> rcoma, granular cell tumor, alveolar soft part sarcoma, hibernoma, oncocytoma, and crystal storing histiocytosis, among others.
Fetal rhabdomyoma
Fetal adenocarcinoma
Uremic fetor
Fetal trimethadione syndrome
Gestational choriocarcinoma
Mixed Müllerian tumor
Heterotopic pregnancy
Embryoma