Aims Incontinentia pigmenti (IP) is an uncommon X-linked dominant neurocutaneous syndrome, lethal in the majority of affected males in utero and variably expressed in females. The authors report a clinical case of IP in a male infant but without the usual genetic mutations.
Methods Case report and review of the literature.
Results A newborn male infant was noted to have a blistering rash on his left lower leg. On examination, there were linearly arranged pustules, vesicles and hyperpigmented macules affecting the dorsal aspect of his left leg and his left axilla. These became verrucous in part at 2 months of age and subsequently resolved leaving linear patches of hyperpigmentation. Aged 9 months, he is otherwise well and thriving on the 75th centile with/without hair, nail or ocular abnormalities and normal development. There is no family history of ocular or neurological disease or rashes in the neonatal period, but his mother does have a few subtle hypopigmented streaks on her right lower leg. On the basis of a history of typical sequential cutaneous lesions and the presence of linear hypopigmentation in his minimally affected mother, a diagnosis of IP was made. His karyotype was 46XY and DNA analysis on blood did not reveal the NEMO Δ 4–10 rearrangement.
Conclusions IP is caused by mutations in the NEMO gene on chromosome Xq28. Clinical presentation varies considerably even among family members ranging from subtle cutaneous signs as in our case through to severe, incapacitating neurological and ophthalmological manifestations. Many male patients have disease limited to cutaneous involvement of one or two limbs.1 Some male cases have Klinefelter's syndrome (XXY) or as we postulate for our case may arise as a result of somatic mosaicism or less deleterious mutations in the NEMO gene.2