Background: A malignant peripheral nerve sheath tumor (MPNST) is a rare sarcoma, characterized by an aggressive course and forms a diagnostic challenge, in view of its varied histomorphology. The present study is a comprehensive analysis, including histopathological spectrum of 63 MPNSTs that forms a substantial study from an Indian perspective.
Materials and methods: Clinicopathological features of 63 MPNSTs, diagnosed during a period from January 2002 to December 2006, at a tertiary cancer referral center in Mumbai, India, were analyzed. Statistical analysis was carried out using SPSS (version 14) and STRATA. Difference in events was noted in 50 cases with selected variables. Disease free survival (DFS) was calculated by Kaplan-Meir analysis at the end of 1 year.
Results: More cases were identified in > 30 years age (36 cases, 57.14%) group; in men (46 cases, 73%), and were deep-seated (38, 60.3%). Ten cases (15.9%) showed stigmata of multiple neurofibromatosis type 1. Average tumor (T) size was 9.9 cm, with 72.9% cases having T size > 5 cm. More cases were of high grade (56, 88.8%) and high stage (22, 34.9%). Histopathologically, most cases showed hypo- and hypercellular areas (marbleized appearance) of doubly indented spindle cells. Two cases showed epithelioid differentiation. Heterologous elements in the form of osteoid, chondroid, pigmented neuroectodermal (1 case), glandular (1 case) and rhabdomyoblastic differentiation (1 case) were identified in 14 cases (22.2%). S-100 protein positivity was noted in 38/54 cases (70.3%). Maximum cases (45, 71.4%) underwent surgery, including wide excisions and amputations (R0) in 20 cases, marginal excisions (R1) in 4, and intracapsular excision (R2) in 1 case. Nineteen cases underwent adjuvant treatment. A total of 29 cases (46%) showed recurrences and 22 (34.9%) showed multifocality and/or metastasis. Four patients succumbed to the disease in 1 year. The DFS was 53.1%. Cases ≤ 30 years of age (P- value = 0.007), T size > 5 cm, and with high grade (P = 0.18) and stage (P = 0.00) showed more recurrences, metastasis, and death.
Conclusions: A MPNST has multifaceted histomorphology. Its objective identification necessitates the incorporation of clinicopathological features and IHC with S-100 protein. Younger age, high grade and stage, and increased T size significantly relate to aggressive disease. Wide excision forms the optimal treatment with options of adjuvant CT/RT in individual cases.