Role of Immunohistochemistry in a Rare Case of Undifferentiated Soft Tissue Sarcoma with Cytohistopathological Correlation

Abstract

Soft tissue sarcomas (STS) constitute a rare subset of malignancies, posing diagnostic challenges due to their varied clinical and histopathological presentations. This case report describes a young adult female who presented with a rapidly growing thigh mass initially misinterpreted as chronic hematoma on ultrasound examination. Subsequent cytological and histopathological correlation revealed features consistent with high-grade sarcoma, necessitating further characterization through immunohistochemistry (IHC). The tumour, displaying spindle cells with pleomorphic nuclei and abundant giant cells, posed a differential diagnosis, including pleomorphic leiomyosarcoma, liposarcoma, rhabdomyosarcoma, and malignant melanoma. Immunohistochemical examination was pivotal, confirming strong Vimentin positivity and a 30% Ki67 proliferation index while ruling out CDK4, Myogenin, MDM2, S100, SMA, and CD34 markers. This case underscores the critical role of IHC in accurate diagnosis and prognosis of challenging STS cases, advocating for a multidisciplinary approach to optimize patient management.