Clinicopathological and immunohistochemical study of the masquerader, malignant peripheral nerve sheath tumours (MPNSTs).

Abstract

Malignant peripheral nerve sheath tumors (MPNSTs) are rare, aggressive neoplasms, comprising 4.34% of all peripheral nerve sheath tumors in our study. Among the five cases analyzed, patients ranged in age from 19 to 57 years, with a peak incidence (40%) in the 20–29-year age group, and a marked male predominance (M:F ratio 4:1). The thorax was the most commonly involved site (60%), followed by the head and neck and extremities (20% each), with tumor sizes ranging from 13 to 16 cm. Clinically, all patients presented with a palpable mass. Radiologically, CT imaging revealed invasive margins in three cases and central enhancement in two. Histopathological analysis demonstrated spindle cell morphology arranged in interlacing fascicles with pronounced nuclear atypia, and necrosis was present in four out of five cases. High mitotic activity, including ≥10 mitoses per 10 high power fields in several cases, indicated the tumors’ aggressive behavior. Immunohistochemically, S-100 protein expression was variable, being positive in only two cases, while SOX-10 was positive in all five, confirming neural crest origin. Additionally, a Ki-67 index ≥20% was observed across all cases, reflecting high proliferative potential and poor prognosis. These findings highlight the importance of integrating clinical, radiological, histological, and immunohistochemical data for accurate diagnosis and assessment of MPNSTs.