Gross pathology The tumor may be seen within the subcutaneous tissues (below the skin), mucosal surfaces or in soft tissue. Within the head and neck, the posterior ear region, skin of the face, and the tongue are the most commonly affected sites (about a 2:1 ratio of soft tissue to mucosa). The tumors are well defined, non-specific usually solitary masses, but when seen in the head and neck (or genital region), they may be polypoid. Tumors range in dimension from a few millimeters up to 12.5 cm, with a mean of about 3.0 cm. Although there are isolated case reports, multifocality is very rare. Microscopic pathology A hematoxylin and eosin stained image (high power) of the short spindle cells of a<unk> .Fetal<unk>  are separated into two histologic types: Myxoid and cellular. However, irrespective of histologic type, these tumors almost never show necrosis or increased mitoses. However, a cambium layer, abnormal mitoses and nuclear pleomorphism is not seen. Cellular<unk> s are composed of bland, primitive spindled cells. The spindle cells are haphazardly arranged primitive, elongated skeletal muscle cells. The cells are set within a well-developed fibromyxoid stroma. A different pattern (intermediate type) is predominantly composed of cells with better differentiation towards skeletal muscle. There are often large ganglion cell-like rhabdomyoblasts showing prominent nucleoli within nuclei that show vesicular chromatin distribution. Another population includes strap-like rhabdomyoblasts with darkly staining pink cytoplasm. Nearly all tumors show short to more sweeping fascicles of spindled rhabdomyoblasts. The tumor cells may infiltrate into adjacent skeletal muscle or fat. It is not uncommon to see peri-neural association, although not perineural infiltration.
Fetal rhabdomyoma
Fetal adenocarcinoma
Uremic fetor
Fetal trimethadione syndrome
Gestational choriocarcinoma
Mixed Müllerian tumor
Heterotopic pregnancy
Embryoma