Leiomyoma, a smooth-muscle tumour, occurs most frequently in the genitourinary and gastrointestinal tracts, less frequently in the skin and more rarely in the deep soft tissues.1 Leiomyoma of the breast or nipple is uncommon and causes little morbidity, therefore it is difficult to find reports that describe its presentation, diagnosis and treatment. From a review of the English literature in 1989, Allison and Dodds2 concluded that there are fewer than 20 reported cases of leiomyoma of the nipple or areola. Since then, Silk, Hena and Pilon,3 Ilie4 and Yokohama and colleagues5 have reported additional cases. I was able to find one reference to a leiomyoma in the retroareolar region.6 I report here a new case of leiomyoma occurring in the retroareolar region in a woman.
A 45-year-old women presented with a well-defined, smooth, firm, tender lump behind the right nipple. The lump measured approximately 1 cm in dimension. She had first noticed it 2 weeks earlier, and it appeared to be increasing in size. Three years before she had had a cyst in the same region that was found to be benign on biopsy. Physical examination of the right breast revealed no apparent calcification, skin distortion, inflammation, retraction of the nipple or nipple discharge. No mammographic or ultrasound abnormalities were demonstrated. The lesion was excised. The specimen included some breast parenchyma, a few lobules and ducts. However, the greater part of the specimen was taken up by a pinktan mass, measuring 1.4 × 1.4 × 0.7 cm and composed of discrete smooth-muscle bundles. There was no histologic evidence of malignancy.
The origin of the tumour reported here is likely from the muscularis mammillae of the nipple or areola, since the location of the lesion was not deep enough to be considered in the parenchyma of the breast. Appropriate treatment for this type of tumour is complete excision. Although leiomyoma can apparently recur if not completely excised,7 there are no reported cases of these tumours progressing to a sarcoma.