Clinicopathological Profile of Spindle Cell STS with IHC Correlation.

INTRODUCTION: Spindle cell soft tissue tumors (STTs) comprise a heterogeneous group of mesenchymal neoplasms characterized by considerable morphological overlap, making accurate diagnosis challenging. Histopathological examination supported by immunohistochemistry (IHC) remains the current diagnostic standard; however, emerging evidence suggests that microRNAs (miRNAs) may provide complementary diagnostic and prognostic biomarkers for these tumors. This study evaluated the clinicopathological spectrum of spindle cell soft tissue tumors and highlights the potential relevance of miRNA-based molecular profiling in improving diagnostic precision. MATERIALS AND METHODS: A prospective observational study was conducted on 55 surgically resected spindle cell soft tissue tumors received at King George's Medical University, Lucknow. Clinical, radiological, and histopathological findings were systematically evaluated. Tumors were classified according to the WHO classification and graded using the French Federation of Cancer Centers Sarcoma Group (FNCLCC) grading system where applicable. Morphology-directed immunohistochemistry employing SMA, S-100, desmin, CD34, myogenin, Bcl-2, EMA, β-catenin, CD99, and CD68 was performed to establish lineage differentiation and confirm histopathological diagnoses. Published evidence regarding miRNA dysregulation in major spindle cell tumor subtypes was integrated to provide molecular context for the observed pathological findings. RESULTS: Among the 55 tumors, 50.9% were malignant, 29.1% intermediate, and 20.0% benign, with a mean patient age of 32.5 years. Malignant tumors occurred predominantly in patients older than 40 years and most frequently involved the lower extremities. Synovial sarcoma and rhabdomyosarcoma represented the predominant malignant spindle cell tumors, whereas schwannoma and neurofibroma were the most common benign lesions. Most malignant tumors were deep-seated, measured ≥5 cm, and were classified as FNCLCC grade 3. Immunohistochemistry was indispensable for confirming lineage differentiation in morphologi-cally overlapping lesions. Furthermore, current evidence indicates that subtype-specific miRNA signatures may complement conventional pathology by improving diagnostic accuracy, prognostic assessment, and future therapeutic stratification. CONCLUSION: Accurate diagnosis of spindle cell soft tissue tumors requires an integrated clinicopathological approach combining histomorphology and immunohistochemistry. The clinicopathological patterns identified in this study provide a valuable framework for future investigations evaluating miRNA expression as diagnostic and prognostic biomarkers in spindle cell soft tissue tumors. Incorporating validated miRNA signatures into routine pathological evaluation may further refine tumor classification and advance precision oncology.