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Waardenburg syndrome
Waardenburg syndrome
Clinical features Waardenburg syndrome is a rare heterogeneous, often but not always autosomal dominant condition characterized by a white forelock and areas of cutaneous hypopigmentation (piebaldism), congenital sensorineural deafness, partial or total iris heterochromia, confluent eyebrows, a broad nasal root, and dystopia canthorum (increase in the distance between the inner angles of the eyelids).1,2 The patches of hypopigmentation are seen in about 20% of patients, are present at birth, involve the face, neck, anterior chest, abdomen, and limbs, and tend to remain stationary throughout life. Hyperpigmented patches are exceptional.3 Some patients lack the white forelock and in a percentage of these there is premature graying of the hair in early adulthood. An association with Hirschsprung disease has been described.4,5 The incidence of clinical manifestations varies in different patients and, based on this, four variants of the syndrome have been described:
โข Waardenburg syndrome I,
โข Waardenburg syndrome II,
โข Waardenburg syndrome III (Klein-Waardenburg),
โข Waardenburg syndrome IV (Shah-Waardenburg). The difference between types I and II is based on the absence of dystopia canthorum in type II. In the latter, neurological abnormalities may also be found.6 Deafness tends to be more common in the latter. In type III the manifestations are similar to type I but in addition there are congenital musculoskeletal abnormalities of the upper limbs including flexion contractures and muscle hypoplasia. In type IV there is absence of dystopia canthorum and an association with Hirschsprung disease.7 In a number of patients with type IV disease there are associated neurological abnormalities including peripheral neuropathy, cerebellar ataxia, mental retardation, and spasticity.8 A subtype of type IV disease is known as PCHW (peripheral demyelinating neuropathy, central dysmyelinating leukodystrophy, Waardenburg syndrome, Hirschsprung disease).
Pathogenesis and histologic features The pathogenesis of nevus anemicus is not clear. It has been suggested that the anomaly is a form of capillary malformation and may result from localized vasoconstriction due to increased levels of catecholamines.3,4,16,17 A recent study demonstrated that the vessels in nevus anemicus do not respond normally to proinflammatory cytokines.18
Histopathology of involved skin appears unremarkable.