By Gary M. White, MD
Incontinentia pigmenti is an uncommon X-linked dominant disorder, lethal in the majority of affected males in utero and variably expressed in females. Some males affected with IP have Klinefelter's Syndrome (47, XXY), but many do not. Some of these males whose karyotype is normal may have a limited form of the mutation that occurred postzygotically.
Female infants are affected first by erythematous, vesicular linear lesions, and then by hyperkeratotic linear plaques, which finally resolve leaving linear and reticulated hyperpigmentation. There may be significant peripheral eosinophilia as seen on a CBC. Subungual hyperkeratosis and tumors may appear, usually after puberty, from 15-25 years of age [CED 2013;38;802-4--CP] but as late as 45 years [JEADV 2016;30;1401]. A large keratotic mass displaces the nail and destroys the distal phalanx. They can easily be confused with subungual warts. Histology of the lesions has shown a KA or SCC-like histology. Sometimes, radiographs show scalloped bone lesions.
Late recurrences of first-stage inflammatory vesiculobullous lesions of incontinentia pigmenti are uncommon but have been reported to occur in the setting of infections, fevers, and vaccinations, including hand, foot and mouth disease.
A skin biopsy showing a blister with eosinophils in the appropriate clinical setting is diagnostic but in general, the diagnosis is made clinically.
Multisystem defects occur with preference for the musculoskeletal system, brain (e.g. epilepsy, mental retardation, hemiparesis and spasticity), eyes (e.g. cataracts, strabismus, nystagmus, optic atrophy, retinal detachment, retinal arteriolar occlusion, subsequent neovascularization and retinal infarction), hair and teeth.
The most serious potential complication is blindness and psychomotor retardation. Since the infant cannot convey symptoms of decreased vision or mental function, a high degree of suspicion should be maintained. No treatment is indicated for the skin changes. Topical steroids may be given for the inflammatory stage or mild keratolytics for the verrucous stage, but in reality, this may be more something for the parents to do as the child is usually not too bothered by the lesions and they will soon resolve.
Potential neurological abnormalities include seizures and motor impairments as well as mental retardation and learning and language disabilities. Head CT or MRI may be indicated here.
The non-cutaneous changes are of most concern and the patient should be evaluated and followed for the associated changes. Genetic counseling should be done. Specifically, 2/3 of patients have dental abnormalities and patients should be evaluated by a pediatric dentist by 2 years of age. Ocular problems occur in about 1/3 and patients should be seen by an ophthalmologist.
Male patient with IP. JAAD February 2007 Volume 56, Issue 2, Pages 264–267
Subungual Keratotic Nodules. JAAD April 2005 Volume 52, Issue 4, Pages 726–729
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