ANSWER: TUBEROUS SCLEROSIS or TUBEROUS SCLEROSIS COMPLEX
This patient's neurocutaneous findings suggest tuberous sclerosis, also called tuberous sclerosis complex (TSC). Hypomelanotic macules and brain hamartomas are considered to be among the salient features of this genetic syndrome.
ETIOLOGY AND PREVALENCE
TSC is a rare multisystem genetic disorder characterized by the growth of hamartomatous lesions in different organ systems. Neoplastic growth occurs primarily in the CNS, eyes, kidneys, and skin. The incidence of TSC is estimated to be 1 in 5000 to 10,000 live births.1 The syndrome occurs with equal frequency in girls and boys, and the number of cases does not vary among ethnic groups.2
TSC is inherited as a mendelian autosomal dominant disorder with complete penetrance and a wide spectrum of phenotypic expressions.2 Mutations involving 2 different genes (TSC1 and TSC2) can each produce the phenotype of TSC. Patients with a TSC2 mutation tend to have more severe phenotypic and neurological involvement than do patients with a TSC1 mutation.1 One-third of cases of TSC are familial. Two-thirds of cases are the result of a new dominant mutation in the affected patient.1-3 Prenatal molecular genetic testing using sequence analysis is available to identify a mutation in the fetus if the TSC-causing allele has been identified in an affected family member.2 Prenatal ultrasonography during the third trimester (after 24 weeks' gestation) can also assist in making the diagnosis by identifying cardiac tumors associated with TSC, known as cardiac rhabdomyomas.2
A wide variability in phenotype is seen among patients with TSC and even within families with affected members. The skin is involved in close to 100% of patients with TSC,3 and cutaneous findings and seizure activity in a newborn can be diagnostic clues. However, any organ system can be involved.1,2 For a summary of the primary manifestations in various organ systems, see the Table.