Dermatofibrosarcoma protuberans of the breast with progressive enlargement during pregnancy: Case report and a brief review of the literature

Dermatofibrosarcoma protuberans (DFSP) is an uncommon low-grade sarcoma that rarely involves the breast and few cases have been reported in literature. It is therapeutically important to distinguish DFSP from other breast malignancies like metaplastic carcinoma and phyllodes tumors. A 37-year-old pregnant woman was referred to the breast clinic for evaluation of an impressive increase of a previously stable breast mass in the second trimester. The lesion was initially thought to be benign, but it grew quite rapidly from a small nodule to a 6 cm, multinodular mass with violaceous discoloration. This gestational growth pattern caused immediate clinical concern and mandated immediate evaluation.
However, the diagnostic follow-up was challenging due to lactational physiological changes of pregnancy which created difficulties in overcoming limitations of imaging presentation. Ultrasound and MRI showed overlap of benign and malignant characteristics, highlighting the fact that imaging was insufficient for a definitive diagnosis, necessitating further evaluation. Core needle biopsy was then performed and revealed a storiform pattern of spindle cell proliferation.  The diagnosis was established based on extensive immunohistochemical (IHC) analysis and molecular findings (FISH test), revealing the pathognomonic COL1A1-PDGFB fusion gene.
Our case was particularly challenging due to concerns related to timing of the surgery during pregnancy, in addition to ensuring en-bloc excision with adequate surgical margins of safety for the mother and fetus. The patient underwent a gross surgical resection; however, the mass recurred locally 14 months post excision, likely due to insufficient surgical margin, emphasizing the necessity of achieving clear margins in the management of DFSP.
The case report underscores the importance of a high index of clinical suspicion in the presence of breast masses with rapid growth in pregnant women, the diagnostic challenge of rare breast sarcomas in pregnancy, as well as the necessity for a comprehensive multi-disciplinary management approach in the overall management of these challenging tumors.