Faculty Bibliography

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

Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder characterized by marked variation in clinical severity. To investigate the contribution to variability by genes either contiguous to or contained within the NF1 gene, we screened six NF1 patients with mild facial dysmorphology, mental retardation, and/or learning disabilities, for DNA rearrangement of the NF1 region. Five of the six patients had NF1 gene deletions on the basis of quantitative densitometry, locus hemizygosity, and analysis of somatic cell hybrid lines. Analyses of hybrid lines carrying each of the patient's chromosomes 17, with 15 regional DNA markers, demonstrated that each of the five patients carried a deletion > 700 kb in size. Minimally, each of the deletions involved the entire 350-kb NF1 gene; the three genes--EVI2A, EVI2B, and OMG--that are contained within an NF1 intron; and considerable flanking DNA. For four of the patients, the deletions mapped to the same interval; the deletion in the fifth patient was larger, extending farther in both directions. The remaining NF1 allele presumably produced functional neurofibromin; no gene rearrangements were detected, and RNA-PCR demonstrated that it was transcribed. These data provide compelling evidence that the NF1 disorder results from haploid insufficiency of neurofibromin. Of the three documented de novo deletion cases, two involved the paternal NF1 allele and one the maternal allele. The parental origin of the single remaining expressed NF1 allele had no dramatic effect on patient phenotype. The deletion patients exhibited a variable number of physical anomalies that were not correlated with the extent of their deletion. All five patients with deletions were remarkable for exhibiting a large number of neurofibromas for their age, suggesting that deletion of an unknown gene in the NF1 region may affect tumor initiation or development

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.