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An Intracranial Leiomyosarcoma in a Child with Neurofibromatosis Type 1

widespread abnormalities in the nervous system, skin and bones. Neurofibromatosis type 1 (NF1 or von Recklinghausen’s disease) is the most common form, with an incidence of 1/35001. Neurofibromatosis type 1 is a disorder with variable phenotypic expression. Some patients may primarily have cutaneous expression, while others may have life-threatening or severely disfiguring complications. The variability in phenotypic expression of this disease is even demonstrated within families. The NF1 gene is located on chromosome 17 and encodes the tumor suppressor gene neurofibromin, a negative regulator of the Ras signaling pathway2. Inactivation of neurofibromin leads to cell proliferation and tumor development. Neurofibromatosis type 1 is associated with both benign and malignant tumours. The most characteristic tumour in NF1 is the neurofibroma, a nerve sheath tumour composed of schwann cells, fibroblasts, mast cells and vascular components3. The risk of malignancy is three-five times greater in NF1 patients than in the general population4. About 30% of the mortality associated with NF1 is due to a malignancy of some kind. Some of the malignancies associated with NF1 include pheochromocytoma, leukemia, melanoma, carcinoid, Wilm’s tumour and soft tissue sarcomas such as rhabdomyosarcoma and fibrosarcoma. Peripheral nervous system (PNS) tumors such as the plexiform neurofibroma and the malignant peripheral nerve sheath tumour are far more common than central nervous system (CNS) tumours in NF1 patients, but the latter can lead to significant mortality and morbidity. Approximately 90% of the CNS tumours associated with NF1 are pilocytic astrocytomas, the majority of which are optic pathway gliomas1,5,6. In addition to the pilocytic astrocytoma, NF1 patients may develop high grade astrocytic neoplasms. It is estimated that 15% of pediatric NF1 patients will have a brain neoplasm of one kind or another, a statistic that is similar to the adult population7. Since NF1 is a known tumour suppressor gene, its inactivation through a variety of different mechanisms could lead to tumorigenesis including malignant transformation. As such, there are numerous case reports demonstrating the association of NF1 and tumour formation. Some of these tumours, however, may occur with the same frequency in NF patients as they do in the general population. It is therefore important to differentiate these tumours in NF patients from those that are truly associated with NF1 where the incidence in the NF1 population is greater than that of the general population. The present case report depicts a child with NF1 in whom a tumour normally associated with NF1, a leiomyosarcoma, was diagnosed in the intracranial compartment. To our knowledge, this is the first intracranial