Intraparenchymal breast leiomyoma and atypical leiomyoma

Abstract

Background: Breast leiomyoma is a rare benign mesenchymal tumor, accounting for less than 1% of all breast neoplasms. Cases of breast atypical leiomyoma is even more rarely reported and its diagnostic criteria together with its clinical courses is not cleared defined.

Case presentation: We described two patients with breast leiomyomas. One has unilateral benign breast leiomyoma, the other one has bilateral breast leiomyomas. For the bilateral case, the left-side tumor was diagnosed as benign leiomyoma while the right-side tumor was diagnosed as atypical leiomyoma. The morphological features that lead to the diagnosis of atypical leiomyoma are its invasive growth pattern, mild nuclear atypia, and mitotic figures up to 3mitoses/10HPF.

Conclusions: Atypical breast leiomyoma appears to behave like benign leiomyoma without recurrence in our study with nine-year follow-up. Due to the limited experience, cases presented as atypical intraparenchymal breast leiomyoma should be closely followed.

Keywords: Atypical leiomyoma; Breast leiomyoma; Case report.

Fig. 1

Benign intraparenchymal breast leiomyoma. A–C Histologic image of leiomyoma in case 1 (H&E × 10, × 100 and × 400)

Fig. 2

Bilateral leiomyoma of breast. A Leiomyoma of left breast. Noted the invasive growth pattern of this tumor including its infiltrative margin and the packed normal mammary glands in it. The infiltrative margin indicated by the black square is magnified in B (H&E, × 10). B Noted the infiltration of this tumor into adipose tissue (H&E, × 200). C Nuclei of tumor cells in high magnificent view showed typical spindle morphology with blunt end which is characteristics for leiomyoma (H&E, × 400). D, E Immunohistochemical stain of SMA and Ki-67 in leiomyoma of left breast. F Leiomyoma of right breast (H&E, × 10)