Piebaldism in Children

Case Report

A 14-year-old adolescent girl presented with multiple asymptomatic light-colored patches on the forehead, bilateral arms, and legs that had been present since birth. The patient reported that the size of the patches had increased in proportion to her overall growth and that “brown spots” had gradually started to form within and around the patches. She noted that her father and paternal grandfather also had similar clinical findings. A review of systems was negative for hearing impairment, ocular abnormalities, and recurrent infections.

Physical examination revealed an otherwise healthy adolescent girl with Fitzpatrick skin type I and homogeneous blue eyes. Large symmetric depigmented patches were noted on the extensor surfaces of the mid legs and mid forearms (Figure). Macules of baseline pigment and hyperpigmentation were irregularly scattered within and at the periphery of the patches. A triangular hypopigmented patch at the hairline on the mid frontal scalp hairline was accompanied by depigmentation of terminal hairs in this region.

Large symmetric depigmented patches on the extensor surfaces of the mid legs (A) and mid forearm (B).

A clinical diagnosis of piebaldism was made and was discussed at length with the patient. Due to the benign nature of the condition and patient preference, no therapeutic intervention was pursued. It was recommended that she apply sunscreen daily for protection of the depigmented areas.

Comment

Piebaldism is a rare hereditary disorder of melanocyte development characterized clinically by the presence of congenital poliosis and leukoderma.¹ The exact prevalence of piebaldism is unknown, but it has been estimated that less than 1 in 20,000 children are born with this condition.² Poliosis circumscripta, traditionally known as white forelock, may be the only manifestation in 80% to 90% of cases and is present at birth.³ The white forelock typically appears in a triangular shape and the underlying skin of the scalp also is amelanotic. The eyebrows and eyelashes also may be involved.³

Characteristically, lesions of leukoderma are well-circumscribed, irregular, white patches that are often accompanied by hyperpigmented macules noted on both depigmented and unaffected adjacent skin.¹ The lesions are classically distributed on the central forehead and anterior trunk, with extension to the flanks, anterior mid arms, and mid legs. Sparing of the dorsal midline, hands, feet, and periorificial area is characteristic.¹

Depigmented patches typically are nonprogressive and persist into adulthood. Additional hyperpigmented macules may develop at or within the margins of the white patches. Partial or complete repigmentation may occur spontaneously or after trauma in some patients.² Some children may develop café au lait lesions and may be misdiagnosed as concurrently having neurofibromatosis type I and piebaldism. If neurofibromatosis type I is suspected, patients should be thoroughly evaluated for other diagnostic criteria of this syndrome, as there may be cases of coexistence and overlap with piebaldism.⁴

Piebaldism is an autosomal-dominant inherited disorder and most commonly develops as a consequence of a mutation in the c-kit proto-oncogene (located on chromosome arm 14q12), which affects melanoblast migration, proliferation, differentiation, and survival.² In piebaldism, the site of mutation within the gene correlates with the severity of the phenotype.⁵ Melanocytes are histologically and ultrastructurally absent or considerably reduced in depigmented patches but are normal in number in the hyperpigmented areas.²

Rare cases of piebaldism have been reported in association with other diseases, including congenital megacolon, congenital dyserythropoietic anemia type II, Diamond-Blackfan anemia, Grover disease (transient acantholytic dermatosis), and glycogen-storage disease type 1a.^1,6 Poliosis alone may be the initial presentation of certain genetic syndromes, including Waardenburg syndrome (WS) and tuberous sclerosis; it also may be acquired in the setting of several conditions, including vitiligo, Vogt-Koyanagi-Harada syndrome, Alezzandrini syndrome, alopecia areata, and sarcoidosis.³