A Boy With a Hyperpigmented Patch and Café au Lait Macules
A 2-year-old boy presented for a well visit. The boy’s development was normal for his age, but the results of a physical examination showed that he had approximately 14 café au lait macules on his left trunk and 2 on his left armpit (Figure 1). A confluent large hyperpigmented patch was present on his mid chest and abdomen, extending around the left side of his back and not crossing the midline. (Figure 2). The boy had no lumps in his skin and no other rashes.
What is the cause of the child’s macules and patch?
(Answers and discussion are on the next page.)
Upon questioning, the boy’s mother reported that at 1 year of age he had been evaluated for neurofibromatosis by an ophthalmologist and geneticist and that testing results were negative. After a subsequent review with the geneticist following the 2-year-old well visit, it was determined that the patient’s presentation fit the diagnosis of segmental neurofibromatosis type 1, a type of neurofibromatosis where the mutation occurs in a somatic cell, producing somatic cell mosaicism and a segmental distribution of surface pigment that follows the lines of Blaschko.1
In this case, it would appear that cutaneous tissue of the left torso was involved in the mutation, but it cannot be said with certainty whether other cell lines have been affected. The boy’s ophthalmology examination results were negative for Lisch nodules, and skin biopsy was not considered necessary for the diagnosis. Future care will include annual follow-ups with a pediatrician, geneticist, and ophthalmologist. Magnetic resonance imaging of the brain has been considered for future evaluation.
Multiple café au lait spots, inguinal and axillary freckling, cutaneous neurofibromas, and Lisch nodules of the iris characterize neurofibromatosis type I. Individuals with the condition may less frequently have serious signs and symptoms such as optic nerve and other CNS gliomas, malignant peripheral nerve sheath tumors, plexiform neurofibromas, vasculopathy, scoliosis, and tibial dysplasia.2
Children without a family history of neurofibromatosis type 1 may not receive an immediate diagnosis, but by 1 year of age, approximately half of children without a family history meet the meet the National Institutes of Health criteria for diagnosis. Manifestations of neurofibromatosis type 1 increase with age, so almost all patients meet diagnostic criteria by 8 years of age. About 50% of individuals with neurofibromatosis type I have learning disabilities, and some children show features of autism spectrum disorder.2,3
Segmental neurofibromatosis is diagnosed in individuals who have features of neurofibromatosis type I restricted to 1 part of the body and whose parents are both unaffected. Worldwide, only about 100 cases have been reported.4,5 The diagnostic criteria for segmental neurofibromatosis were established in 1982 by Riccardi to include the following: pigmentary abnormalities (café-au-lait macules and/or axillary freckles) and/or neurofibromas in a single unilateral segment of the body, with no crossing of the midline; no known family history of neurofibromatosis; and no systemic involvement.6
However, these criteria were further clarified in future publications to create subtypes of segmental neurofibromatosis.7 The most common presentations of cutaneous findings in segmental neurofibromatosis are asymptomatic neurofibromas in a dermatomal distribution (most commonly cervical), café-au-lait macules, and axillary freckling.4 Biopsy of café-au-lait spots typically shows increased melanin pigment in the basal layer of the epidermis, sometimes with an underlying neurofibroma in the dermis. Although skin biopsy would be necessary only in atypical segmental pigmentation, it could be employed to obtain samples for confirmation of neurofibromatosis type I diagnosis by DNA testing.
Guidelines have been suggested for preventive health care of children with neurofibromatosis type I8,9 but not specifically for segmental neurofibromatosis. Reasonable extrapolation of general guidelines to the involved segment can be followed, including annual developmental assessment, blood pressure measurement, and ophthalmologic examinations.10 Monitoring can be less frequent with age, but parents should be educated on possible complications.
Bailee Olliff is a fourth-year medical student at the University of South Florida, Morsani College of Medicine in Tampa, Florida.
Lana Soylu, MD, FAAP, is an associate professor of pediatrics at the University of South Florida, Morsani College of Medicine in Tampa, Florida.
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