Malignant peripheral nerve sheath tumour with multilineage divergent differentiation including a neuroblastic component

Abstract

Malignant peripheral nerve sheath tumor (MPNST) occurs either sporadically, in patients with neurofibromatosis type 1 (NF1), or following therapeutic radiation therapy; MPNST often arises from a peripheral nerve or a pre-existing neurofibroma.1,2 In addition to mutations in NF1 and CDKN2A, MPNST frequently harbors inactivating mutations in SUZ12 or EED, resulting in PRC2 (polycomb repressive complex 2) dysfunction and loss of histone H3 lysine 27 trimethylation (H3K27me3), most often seen in high-grade sporadic and radiation-associated tumors.2-4 Although the diagnosis of MPNST can be challenging, especially when there is neither a history of NF1 nor a clearly identifiable origin from a pre-existing neurofibroma, it can usually be recognized on the basis of the classic histological features, in conjunction with H3K27me3 loss by immunohistochemistry.