The skin changes are the most characteristic and common features in IP. They are described in four stages. In all the stages, the Lesions appear in lines on the arms and legs or a swirled pattern on the trunk. They can be on the face and scalp.
1) The first stage of IP may be present at birth or appear during early infancy. This phase consists of redness or inflammation of the skin (erythema), blisters, and boils, most often affecting the extremities and the scalp. It can fade and come back again and again, commonly when there is an illness with fever. These recurrences may happen for years.
2) The second stage may overlap the first and may be present at birth. During this phase, the Blisters develop a raised, wart-like (verrucous) appearance, and the Lesions look like warts. There can be thick crusts or scabs with healing and areas of darkened skin (increased pigmentation). The extremities are involved almost exclusively in this stage. These recurrences may happen for years.
3) The third stage may be present at birth in a small number of affected individuals, but usually appears between the ages of 6 and 12 months. In this phase, the skin is darkened (hyperpigmented). On the trunk, the dark is sometimes described as a “marble cake” appearance. The hyperpigmentation does not necessarily happen where the stage I and II rashes happen. The heavy pigmentation may fade over time, though they are permanent in many patients.
4) The “atrophic stage” is called the fourth stage, but there are suggestions that it may actually be present, but not obvious, at birth. These skin changes are pale or hypopigmented and hairless. There may be a diminished number of sweat glands.
Between 50 to 75 percent of individuals with IP have dental abnormalities. These abnormalities include a delay in the eruption of primary teeth; abnormal contours of teeth, giving them a peg-like or cone-shaped appearance; or the congenital absence of both primary and secondary teeth (anodontia); or small teeth, (microdontia).
Some individuals with IP have ridged, pitted, thickened (onychogryposis), or missing nails on the hands and/or feet. In some patients, painful growths may develop under the nail. These changes can be permanent.
Approximately 50 percent of individuals with IP have abnormal bald patches on the scalp (alopecia). This may happen where the stage one and two Lesions have left scars or as part of a congenital skin dysplasia. The hair may be coarse, wiry, and/or lusterless.
Nearly one-third of individuals have eye (ocular) abnormalities. The most serious, but least frequent, is a congenitally small, abnormal eye. In any patient there can be an abnormality in the growth of blood vessels in the membrane lining the eyes (retina). If it is going to occur, this typically appears before the age of five. This problem may be treated if detected early. If left untreated, it may cause retinal detachment leading to permanent visual impairment or total blindness.
The majority of individuals with IP will have no involvement of the nervous system. Severe neurologic complications can occur as a consequence of IP, the most serious of which is congenital or neonatal strokes. Some affected individuals may experience episodes of uncontrolled electrical disturbances in the brain (seizures). About 30 percent of children with IP will have slow motor development, Muscle Weakness in one or both sides of the body, intellectual disability, and/or seizures.
Abnormalities in the development of the breast, ranging from extra nipples to complete absence of the breast, are sometimes seen in individuals with IP.
There are anecdotal reports of heat intolerance or lack of normal Sweating in people with IP, but this has not been formally studied.