Incontinentia pigmenti (IP) is a rare X-linked dominant genodermatosis that is typified by distinctive cutaneous findings and often by abnormalities of teeth, hair, nails, eyes, musculoskeletal system, and central nervous system. The gene that is mutated in patients with IP has been mapped to Xq28 and encodes the NF-κB essential modulator, NEMO. Female patients with IP show functional mosaicism and cutaneous manifestations follow Blaschko’s lines of ectodermal embryologic development. The condition is generally considered to be lethal in utero in male fetuses, suggesting that having some normal gene expression is critical for survival.

We observed 9 boys with IP. All had normal karotypes and no apparent family history of IP. In 8 of these 9 patients, lesions were localized to one extremity at presentation. The diagnosis was confirmed by histopathologic examination that showed eosinophils within intraepidermal, multiloculated vesicles. One of the boys later developed dental and neurologic abnormalities.

The case series was small and the workup for these patients from different sites was not uniform.

Male individuals may show cutaneous and noncutaneous features of IP in a limited distribution that allows survival. Postzygotic mutation/somatic mosaicism is the likely mechanism. Given the potential sequelae associated with this condition, continuing follow-up of these patients is recommended.