Two cases of male nipple leiomyoma: idiopathic leiomyoma and gynecomastia-associated leiomyoma

We describe 2 cases of male nipple leiomyoma. A 70-year-old man had a painful subcutaneous tumor on his left nipple of 6 months duration. Histopathology disclosed dermal spindle cells with oval-shaped nuclei forming interlacing bundles with irregular pattern. Glandular elements were absent. The spindle cells were positive to α-smooth muscle actin, desmin, and vimentin. Estrogen receptor (ER) and progesterone receptor (PrR) were negative. We diagnosed this case as male leiomyoma of the nipple. Another patient was a 61-year-old man with gynecomastia induced by spironolactone of 6 months duration. He also had a painful nodule on his left nipple and histopathology disclosed spindle-shaped tumor cells as in the previous patient. The tumor was accompanied by glandular elements in the deep dermis and subcutaneous tissue, which showed apocrine secretion and were positive for α-smooth muscle actin, ER, and PrR. These glandular elements were interpreted as mammary gland. But ER and PrR stain did not show positive results for leiomyoma in the upper dermis. To the best of our knowledge, this is the first report of male idiopathic and gynecomastia-induced leiomyoma with ER and PrR staining.