Malignant peripheral nerve sheath tumors (MPNST) in NF1-affected children

Malignant peripheral nerve sheath tumors (MPNST) constitute a heterogeneous group of malignant tumors that probably arise from cells of the peripheral nerve sheath. Association of MPNST with neurofibromatosis type 1 (NF1) is frequently reported. MPNST contribute significantly to the reduced life-span of NF1-patients. At present there are only sparse data on MPNST in NF1-children. The aim of this study was to determine the outcome of children affected with NF1 who developed an MPNST.

Over the period of 1985 to 2005, we followed 52 NF1 patients with MPNST at our outpatient department. All patients were diagnosed and re-evaluated according to the updated NIH diagnostic criteria for NF1.

Out of this cohort, 8 patients with MPNST were aged 1 to 17 years at the time of MPNST diagnosis (mean age: 12 years; 5 girls and 3 boys). We noticed the following characteristics: MPNST arose from plexiform neurofibromas (PNF) with invasive or displacing growth pattern on MRI. Many patients reported pain and neurological deficits at the time of presentation. Diagnosis of MPNST in this age group took longer compared to adults. This cohort did not show longer survival periods than adults with MPNST. Adjunctive treatment with chemotherapy or radiation had no lasting effect. The overall survival time of this small cohort was 30.5 months. Those children who died showed a median survival time after diagnosis of 20 months. The longest survival of 112 months was achieved for a girl who presented with MPNST of the distal upper arm and underwent amputation. The NF1 mutation analysis in the MPNST pediatric age group revealed the same mutational spectrum as the adult group.

Our data reveal MPNST in children with NF1. Children cannot verbalize physical alterations adequately; therefore the correct diagnosis might be hampered in these patients. Unresolved complaints of children with NF1 should be investigated thoroughly due to the risk for malignancy in NF1.