Leiomyoma of the Nipple: A Rare Entity at Rare Site

Cutaneous leiomyomas are benign and rare smooth muscle tumors. Genital leiomyoma includes leiomyomas located in the nipple, scrotum, areola or vulva. Nipple leiomyomas are the least common genital leiomyomas and are commonly seen to occur in middle-aged women. Here, we present a case of a 40-year-old female complaining of a growth over the right nipple for six months. On local examination, it was a 1cm x 1cm growth on the lateral aspect of the nipple. Finally, a treatment plan of complete excision was done. Grossly, it was a well-circumscribed skin-covered soft tissue bit with a skin flap measuring 0.6cm x 0.6cm and soft tissue measuring 0.6cm x 0.5cm x 0.2cm. Histopathological examination revealed a skin-covered section with dermis showing a well-circumscribed unencapsulated lesion that showed intersecting fascicles of spindle cells with no atypia or mitoses noted. Microscopically, the growth had tumor-free resection margins. Immunohistochemical confirmation with S100, smooth muscle actin (SMA) and caldesmon was done. Diagnosis of nipple leiomyoma was given with strong SMA positivity. Nipple leiomyoma is a rare, benign lesion and needs to be correctly diagnosed microscopically. Biopsy and immunohistochemistry is a confirmatory investigation that can lead to timely management of the patient.