Desmoid Breast Tumor after Breast-Conserving Surgery for Breast Cancer—A Case Report—

Abstract

A 56-year-old patient presented with a hypoechoic mass in the breasts. The patient had a history of invasive mucinous pT1cN0M0 Stage I carcinoma in the lower outer quadrant of her left breast and had undergone lumpectomy and sentinel lymph node biopsy, followed by postoperative irradiation therapy and endocrine therapy. Palpation, mammography, and sonography suggested metachronous ipsilateral breast cancer. The needle biopsy specimen showed proliferation of spindle-shaped cells with low nuclear atypia and low mitotic counts. Radiological findings revealed a growing heterogeneous mass. Based on the combined imaging and biopsy results, desmoid-type fibromatosis was suspected. Tumor resection was performed with a sufficient surgical margin. Postoperative diagnosis based on the surgical specimen confirmed desmoid-type fibromatosis. Desmoid-type fibromatosis is difficult to diagnose using small biopsy samples ; thus, appropriate treatment should be administered based on pathological and radiological assessments.