Brainstem lesions in neurofibromatosis type 1

The presence of multiple, nonenhancing areas of hyperintensity without mass effect are well recognized on magnetic resonance imaging scans in children with neurofibromatosis type 1 (NF1). Focal regions of brainstem enlargement with or without contrast enhancement are considerably less frequent; the neuroimaging characteristics and natural history of these lesions in patients with NF1 are poorly understood. The objective of this study was to define the clinical and radiographic course of brainstem lesions in children with NF1.

We retrospectively reviewed the neuroimaging studies of all patients with NF1 between 2000 and 2006 to determine the prevalence of brainstem lesions. Clinical features, previous treatments, and neuroimaging studies of the brainstem lesions were evaluated.

A total of 125 patients underwent neuroimaging studies; of these, 23 patients (18.4%) showed evidence of brainstem mass lesions and had follow-up magnetic resonance imaging scans available for review. Eight patients in this cohort received additional treatment with surgery, radiation, or chemotherapy. Of these, two patients underwent surgery for lesions distant from the brainstem, and six patients underwent treatment that included the brainstem and were thought to potentially affect the natural history or progression of the brainstem abnormality. With a median follow-up period of 67 months for untreated patients (17 out of 23) and 102 months for patients who received therapy (six out of 23), only one previously untreated patient experienced radiographic and clinical progression. All patients but one remain alive.

We conclude that brainstem lesions in NF1 are prevalent and behave in a biologically indolent nature; most do not require therapeutic intervention.