Malignant fibrous histiocytoma of the chest wall masquerading as medullary breast carcinoma: a case report.

Background: Cytologic diagnosis of malignant fibrous histiocytoma can be problematic, as these neoplasms are known to mimic multiple other conditions.

Case: A fine needle aspirate from a 60-year-old woman was diagnosed at 2 institutions as medullary carcinoma of the breast. The patient received neo-adjuvant chemoradiotherapy before the tumor war excised. Gross pathologic examination and histomorphology on routine staining were compatible with the cytologic diagnosis. The accurate diagnosis of pleomorphic-storiform-type malignant fibrous histiocytoma was a surprise and was established with immunocytochemical stains. In retrospect, it was thought that clinical and radiologic overlap, creating a high index of suspicion for a breast neoplasm and compounding the cytologic appearance of a medullary carcinoma with spindle cell metaplasia and syncytial cells, was responsible for the error.

Conclusion: This case highlights a potential cytodiagnostic pitfall and the importance of establishing a definitive tissue diagnosis in the face of equivocal cytologic findings.