Recurrent radiation-associated leiomyosarcoma after postoperative radiotherapy for breast invasive ductal carcinoma: a case report and literature review.

Radiation-associated leiomyosarcoma has a poor prognosis. Fewer than 20 cases of radiation-associated leiomyosarcoma of the breast have been reported in the literature to date. We report the first case of recurrent radiation-associated leiomyosarcoma after invasive ductal carcinoma postoperative radiotherapy. A 45-year-old female patient with no familial history of cancer underwent breast-conserving surgery (BCS) and dissection of axillary lymph nodes for invasive ductal carcinoma in the right upper outer region in 2014. After the operation, she received adjuvant chemotherapy followed by radiotherapy and endocrine therapy. She came to our institution for a lump in the right breast radiation region in 2019. Ultrasonography revealed an oval mass, with ill-defined borders, irregular margins, and speculation at 6 o'clock direction of the right breast, approximately 2.5 cm from the nipple. Ultimately, excisional biopsy established the pathological diagnosis of leiomyosarcoma. The female then underwent simple mastectomy of the right breast. The patient received no radiation or chemotherapy after the simple mastectomy. After 13 months of follow-up, a lump was found in the right chest wall and axillary levels of the radiation region. Excisional biopsy confirmed the pathological diagnosis of leiomyosarcoma. This rare case indicated that simple mastectomy seemed to be inadequate treatment for radiation-associated leiomyosarcoma.