Author: Dr Stanley Leong, Dermatology and Paediatric Registrar, NZ (2023).
Reviewing dermatologist: Dr Ian Coulson (2023). Edited by the DermNet content department.
A 12-week-old girl presented with a persistent rash on the thigh and armpit since her birth. Her parents had noted that she appeared persistently irritable, with no social smile, and was unable to fix on and follow objects or faces. She had a normal antenatal and birth history.
On examination, she had linear verrucous plaques with a few vesicles over her right thigh and left armpit.
The likely diagnosis is incontinentia pigmenti (IP). It is a rare genetic condition characterised by skin, eyes, teeth, and CNS abnormalities.
The characteristic skin lesions of IP present at birth or develop in the first few weeks of life in about 90% of patients and tend to be linear or follow the lines of Blaschko.
Incontinentia pigmenti is an X-linked dominant disorder, caused by mutation in the NF-kB essential modulator (NEMO or IKBKG) gene, which encodes for a protein that protects against TNF-alpha-induced apoptosis.
Male patients with milder NEMO mutations may present with hypohidrotic ectodermal dysplasia with immunodeficiency.
IP has 4 stages (some of which may be absent or overlapping) of cutaneous finding that follow the lines of Blaschko (with the exception of stage 4).
