de Vasconcelos RAT, et al. - The recent discovery of a crucial role of mast cells in the tumor onset of neurofibromatosis type 1 (NF1)-associated neurofibromas and malignant peripheral nerve sheath tumors (MPNSTs), confirmed in both experimental and human studies, led researchers to determine mast cell density (MCD), microvascular density (MVD), and proliferation index (Ki-67) in MPNST in this present study. They also intended to correlate histological staining to clinical data and survival in patients with and without NF1. From 29 patients, 34 formalin-fixed paraffin-embedded MPNST tissues were considered eligible. They found a negative correlation of NF1 status, tumor size, and MVD in the tumor periphery to survival. A decreased overall survival was reported in relation to MVD in the tumor periphery, as corroborated in multivariate analysis. An independent occurrence of angiogenesis in MPNST was indicated by the observed diverse mast cell and microvascular distributions. No clarity was gained regarding the role of mast cells in tumor progression. Also, mast cells lacked prognostic value. Prognostic value of higher MVD was evident, along with possible therapeutic implications in MPNST.