Vulvar fetal rhabdomyoma mimicking 46XX sex differentiation disorder.

Rhabdomiomas are rare mesenchymal benign tumors of striated muscle origin. Setting aside the cardiac (most atrial) rhabdomiomas typically associated to neurocutaneous syndromes (tuberous sclerosis), extracardiac rhabdomyomas appear clinically as a subcutaneous nodule or as a submucosal polypoid lesion. Among them, three main histologic subtypes can be differentiated on the basis of the degree of tumor differentiation: 1) fetal rhabdomioma, usually diagnosed during childhood and almost exclusively located in the in the head and neck region with rare reports in other locations; 2) adult rhabdomioma; and 3) genital rhabdomioma, reported to occur in the lower genital tract of young and middle-aged women and, exceptionally, in children (5).