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A 21-year-old woman with neurofibromatosis type 1 (NF-1) had a unilateral congenital Horner's syndrome with resultant hypopigmentation of the affected iris. Lisch nodules, which are melanocytic hamartomas, were similar in number, size, and pigmentation in both eyes. The present findings suggest that the formation of Lisch nodules is not influenced by the presence or absence of sympathetic innervation of the iris

Primary central nervous system (CNS) lymphoma, an otherwise rare pediatric tumor, has been reported with increasing frequency in children with acquired immune deficiency syndrome (AIDS). With current therapy, the outcome of this disease is invariably fatal. The authors present a case of primary CNS lymphoma in a 3.5-year-old girl with AIDS who received treatment with total brain irradiation. After treatment, the patient's mental status improved, the seizures resolved, and she had no further progression of her neurologic symptoms until she died of pneumonia 6 months later. The autopsy revealed a necrotic mass at the site of the original tumor. The brain stem and spinal cord, unirradiated, contained lymphomatous lesions. The patient had extensive fibrinoid necrosis and leukoencephalopathy that were consistent with radiation-induced CNS damage. Coexisting AIDS encephalopathy also contributed to the patient's CNS injury. Effective palliation of CNS lymphoma in children with AIDS may be obtained with cranial irradiation. Pediatric AIDS patients may show more severe tissue effects from irradiation than unaffected children.

Von Hippel-Lindau disease (VHL) is an autosomal dominant disorder with inherited susceptibility to various forms of cancer, including hemangioblastomas of the central nervous system, phaeochromocytomas, pancreatic malignancies, and renal cell carcinomas. Renal cell carcinomas constitute a particularly frequent cause of death in this disorder, occurring as bilateral and multifocal tumours, and presenting at an earlier age than in sporadic, non-familial cases of this tumour type. We report here that the VHL gene is linked to the locus encoding the human homologoue of the RAF1 oncogene, which maps to chromosome 3p25 (ref. 4). Crossovers with the VHL locus suggest that the defect responsible for the VHL phenotype is not a mutation in the RAF1 gene itself. An alternative or prior event to oncogene activation in tumour formation may be the inactivation of a putative 'tumour suppressor' which can be associated with both the inherited and sporadic forms of the cancer. Sporadic renal cell carcinomas have previously been associated with the loss of regions on chromosome 3p (refs 5, 6). Consequently, sporadic and VHL-associated forms of renal cell carcinoma might both result from alterations causing loss of function of the same 'tumour suppressor' gene on this chromosome