Malignant peripheral nerve sheath tumors (MPNSTs) are sarcomas on peripheral nerves or nerve sheath. These MPNSTs can occur on any cell type and differs from one to other. A sarcoma is regarded as MPNST only when it is raised on the peripheral nerve or it exists on neurofibroma. MPNSTs usually present as an enlarging palpable mass. Pain is a variable complaint. Rapid enlargement occurs more often in the setting of NF1 and should raise concern for malignant degeneration of a neurofibroma.
In Hong Kong identified 123 Chinese patients with neurofibromatosis type 1, diagnosed at a median age of 4.9 years (range, 0.1-16.1 years); 75 (61%) were males. They were followed up for a median of 9.7 years (range, 0.2-27.6 years). Most (80%) of the patients participated in our surveillance programme. Twelve patients developed malignancies at the ages of 0.8 to 41.6 years.