NF1 and malignant peripheral nerve sheath tumor: Adverse prognostic factors are truncal location, tumor size > 5 cm, local disease recurrence at presentation, high-grade histology according to the Fédération Nationale des Centres de Lutte Contre le Cancer classification, NF1-associated MPNST, radiation-induced MPNST, and heterologous rhabdomyoblastic differentiation (triton tumor) (LaFemina et al. 2013; WHO Classification of Tumours Editorial Board 2020; Guellec et al. 2016; Miao et al. 2019).