CASE OF THE MONTH
56 year old female presented with a left breast mass. Histologic sections of the core biopsy show a cellular spindle neoplasm with a storiform pattern. Necrosis is not seen and mitotic figures are not conspicuous. In the excisional biopsy, tumor cells infiltrate between breast ducts and amongst lobules of fat imparting a honeycomb pattern. Immunoperoxidase stains show that the tumor cells stain strongly positive with CD34 and BCL-2. No staining is seen with S100, Cam 5.2, P63, CK5, SMA, Desmin and Estrogen Recptor. The morphologic features and immunoperoxidase staining pattern are most compatible with a dermatofibrosarcoma protuberans (DFSP).
DFSP is a low-grade sarcoma which typically occurs in the trunk and extremities in the second to fifth decades of life. Rare cases have been reported to occur in the breast where it typically demonstrates a slow infiltrative growth. These tumors rarely metastasize but have a high rate of local recurrence if incompletely excised. Complete excision with wide margins is the cornerstone of treatment.