Incontinentia pigmenti (IP) is a multisystem disorder, in which cutaneous symptoms can be accompanied by dental, ocular, and central nervous system defects. In adults, the clinical diagnosis of IP is based principally on the late onset of stage 4 lesions and their association with dental, nail, ocular, or central nervous system anomalies. Nevertheless, these lesions are often unrecognized.

Our aim was assessment of IP manifestations in adults to clarify diagnostic criteria for mild forms of the disease, to help physicians detect adult IP in the presence of subtle lesions and avoid misdiagnosis.

We conducted clinical and histologic examination of 25 adults with IP and nuclear factor-κB essential modulator gene rearrangement or mutations.

Linear atrophic, hypopigmented, and hairless lesions (stage 4) are constant in adults. Apoptotic keratinocytes in the epidermis or dermis and atrophic hair follicles, with absence of arrector pili muscles, are frequently observed. In contrast, nipple anomalies are rare.

We were unable to determine the age of the onset of IP stage 4 lesions.

Skin manifestations are constant in adult patients with IP. Histology is characteristic and could be considered as a minor diagnostic criterion of IP. Nipple anomalies also may be considered as a minor criterion. Detection of such subtle manifestations can evoke IP in patients with repeated miscarriages or unexplained neurologic manifestations.