Botryoid-type of embryonal rhabdomyosarcoma of the proximal and mid ureter in an adult woman.

We report a unique case of botryoid-type embryonal RMS of the proximal and mid ureter in a pregnant 29-year-old woman. The ureteral polyp consisted of a malignant small blue round cell tumor with a myxoid background and contained evidence of foci of immature cartilage and aggregates of epithelial cells reminiscent of hair follicle. Immunohistochemical stains for myogenin and desmin confirmed skeletal muscle, or rhabdomyoblastic, differentiation. The compact epithelial cell fragments reminiscent of hair follicle differentiation were positive for p40. Treatment included 6 cycles of adjuvant chemotherapy (vincristine, actinomycin and cyclophosphamide (VAC). No recurrent or metastatic disease was identified post-surgery.