Aspiration cytology of fibrosarcomatous variant of dermatofibrosarcoma protuberans with osteoclastlike giant cells in the chest wall: a case report

BACKGROUND: A case of fibrosarcomatous variant of dermatofibrosarcoma protuberans (FS-DFSP) with osteoclastlike giant cells involved the dermis and subcutaneous tissue of the chest wall. This case was misdiagnosed as primary breast tumor clinically and had cytologic features similar to those of the metaplastic breast carcinoma (MRBC). CASE: A 53-year-old female presented with a nodular breast mass enlarging slowly over a long period of time and growing rapidly for about 3 months. The aspirates showed high cellularity with both individually scattered and fascicular arrays of spindle cells. A few multinucleated giant cells without nuclear atypia were intermixed with dissociated spindle cells. There was no epithelial component in the smear. Cytologic evaluation suggested the possibility of a low grade spindle cell sarcoma as well as MBC. Subsequently, the patient underwent modified radical mastectomy, and the diagnosis of FS-DFSP was made. CONCLUSION: Distinguishing FS-DFSP with osteoclastlike giant cells from other spindle cell tumors of the breast, especially MBC showing predominantly spindle cell components, may pose significant challenges to the pathologist. However, clinical and radiologic findings and a meticulous search for other components raised the possibility of FS-DFSP on aspiration cytology.