Multiple brain metastases from malignant peripheral nerve sheath tumour (MPNST)

Malignant peripheral nerve sheath tumours (MPNSTs) are rare soft tissue neoplasms arising from elements of the nerve sheath that often occur in the context of neurofibromatosis (NF) type 1. Their poor prognosis results from high local recurrence rate and distant dissemination. Nevertheless, the brain metastases are exceptional. We are presenting an unusual case of intrathoracic MPNST in a 33-year-old man with a five-year clinical course characterised by multiple times local recurrences of primary tumour and multiple remote metastases into the brain structures, thyroid and suprarenal gland. Moreover, the cerebellar metastasis regrew in spite of its total excision. Histologically, brain metastatic tumours were composed of spindle cells closely arranged in interlacing and woven fascicles. This highly cellular nerve tissue exhibited an advanced nuclear hyperchromasia and a high mitotic activity. The tumour exhibited rich delicate reticulin network. The schwannian nature of brain metastases has been confirmed by immunohistochemical findings showing S-100 protein and GFAP expression and ultrastructural evidences of the pericellular basal lamina.