de Vasconcelos RAT, et al. - Researchers assessed mast cell density (MCD), microvascular density (MVD), and proliferation index (Ki-67) in malignant peripheral nerve sheath tumor (MPNST), as well as correlated histological staining to clinical data and survival in patients with and without neurofibromatosis type 1 (NF1). They analyzed 34 formalin-fixed paraffin-embedded MPNST tissues from 29 patients. Using a computer-based quantitative algorithm (Aperio ImageScope), they analyzed MCD, MVD, and Ki-67 labeling index (LI) in all stained tissues. An even distribution of MCD, MVD, and Ki-67 LI throughout tumor tissue was found. Findings revealed a negative correlation of NF1 status, tumor size, and MVD in the tumor periphery to survival. A decreased overall survival was reported in multivariate analysis in relation to MVD in the tumor periphery. Overall, no clarity was gained regarding the role of mast cells in tumor progression and it lacked prognostic value. With possible therapeutic implications in MPNST, the prognostic significance of higher MVD was shown.