Clinical, Radiological and Pathological Features of Desmoid Tumor of the Breast: Case Report

Desmoid tumor of the breast (DTB), also referred to as desmoid-type fibromatosis, is a rare tumor with an unknown etiology, imaging findings of which are often confused with breast cancer. The aim of this report is to present a case of DTB with its clinical, radiological, and pathological features. A 42-year-old woman with Turner syndrome, who had undergone bilateral saline-filled breast implantation surgery, presented with a complaint of a lump in her left breast. The patient underwent mammography (MG), ultrasound (US), and dynamic contrast-enhanced magnetic resonance imaging (MRI). The MG examination revealed afocal asymmetric density in the upper middle quadrant of the left breast. A core biopsy was performed on the irregularly shaped spiculated mass identified on US, and the results indicated either cellular fibroadenoma or a phyllodes tumor. On MRI, the mass was hypointense on T1-weighted and short tau inversion recovery (STIR) sequences. The dynamic MRI scan revealed a type 1 enhancement curve, while the apparent diffusion coefficient (ADC), fractional anisotropy (FA) and mean diffusivity (MD) values obtained from diffusion and diffusion tensor imaging were similar to those of the surrounding parenchyma. The mass was removed while preserving the implant, and the pathology results confirmed a diagnosis of DTB.The pathology report indicated microscopic proximity to the cauterized edge, but there was no evidence of recurrent mass detected on the follow-up US performed six months later. This is the first case of DTB reported in a patient with Turner syndrome. DTB is a rare tumor that can often be confused with breast cancer based on clinical and radiological findings, and it may not be accurately diagnosed by core biopsy alone. In cases where a clean surgical margin cannot be achieved, close follow-up and intervention may be considered when recurrence is observed.