Benign fibrous histiocytoma arising from the right shoulder: Is immunohistochemical staining always required for a definitive diagnosis?

INTRODUCTION: Fibrous histiocytomas are divided into two subgroups: malignant and benign fibrous histiocytomas (BFHs). BFH is one of the most common tumors of the superficial and deep soft tissues; it is commonly found on the skin and presents as a slow-growing solitary nodule made up of a mixture of fibroblastic and histiocytic cells. PRESENTATION OF CASE: In this study, we present the case of a 45-year-old female who was histopathologically diagnosed with dermatofibrosarcoma protuberans (DFSP) and received radiotherapy, but whose diagnosis was changed to BFH based on subsequent immunohistochemical analyses. DISCUSSION: BFH is a mesenchymal soft-tissue tumor with fibroblastic and histiocytic differentiation. Differential diagnosis for BFH found in deeper tissues includes other aggressive fibrohistiocytic lesions, such as DFSP and malignant fibrous histiocytoma. Differentiating among these tumors is crucial in selecting the correct surgical strategy and patient management in the postoperative period. In most cases, the pleomorphism and atypical mitotic activity seen histopathologically are sufficient for the differentiation between benign and malignant tumors. Immunohistochemical staining methods should be used in cases that are difficult to diagnose. The treatment of choice for BFH is wide resection of the tumor, which results in an excellent prognosis and low recurrence rate. In agreement with cases reported in the literature, our case confirms that wide excision is adequate to prevent the recurrence of the tumor.
CONCLUSION: Although benign fibrous histiocytomas is rare, it must be considered in the differential diagnosis of tumors arising from the soft-tissue.