Intraparenchimal Leiomyoma of the Breast.

The most common location of the leiomyoma is uterus, small bowel and the esophagus, however they can occur in any organ. Intraparenchimal leiomyomas of the breast are very rare and only 30 cases were reported in the literature. These histologically benign tumors, may mimic malignancies and therefore may present a diagnostic challenge. Here, we present two new cases. The first case was a 50-year-old woman presented with a 4 cm firm mass in her right breast with discrete localized skin thickening/retraction. The second case was a 35-year-old woman presented with a painless palpable lump in the lower outer quadrant of her right breast. Physical examination, mammography and ultrasound as well as surgical excision were performed in both cases. According to histologic examination and immunohistochemical analysis, a diagnosis of smooth muscle tumor of the breast was made. These tumors clinically and radiologically mimic other breast lesions.  Neither imaging studies nor palpation allow distinction between benign and malignant tumors.