Chapter 228: Incontinentia Pigmenti

Patient Story

A 6-day-old girl is brought by her parents to the emergency department for a rash on her arms and chest. The parents noted that over the past 3 days, the baby has had intermittent episodes of right eye deviation and upper extremity stiffening. These episodes lasted approximately 30 seconds, occurred approximately 3 times per day and were associated with cyanosis. The family history was notable for seizures in a maternal aunt. On physical examination the infant was quiet, seemingly withdrawn with stable vital signs. The infant had erythematous papules and vesicles, some of which had eroded with crusting on the arms and anterior chest (Figure 228-1). A direct fluorescent antibody test and culture from the lesions were negative for herpes simplex virus. Skin biopsy of the lesions showed spongiotic dermatitis with many eosinophils and large dyskeratotic cells. Based on the skin lesions and the neurological manifestations, the infant was diagnosed with incontinentia pigmenti. Genetic, neurologic, and ophthalmology consults were obtained.

Introduction

• Incontinentia pigmenti (IP) is an X-linked dominant systemic disease, usually lethal in males, and characterized by skin involvement at birth in 50 percent of cases. IP is a rare genodermatosis that presents in the neonatal period.

• The disease involves tissues of ectodermic and mesodermic origin including cutaneous tissue, teeth, eyes and the central nervous system (CNS), amongst other organs.¹

Synonyms

Bloch-Sulzberger syndrome.

Epidemiology

• The incidence of IP is 1 case per 40,000.¹ It is more common in Caucasians than other ethnicities.

• Because IP is an X-linked dominant disease, affected male fetuses usually do not survive, and therefore over 97 percent of living affected individuals are female.

• IP has high penetrance. Most persons with IP begin to express the phenotype within a few months of birth.²

Etiology and Pathophysiology

• This X-linked dominant disorder is caused by mutations in the gene known as NEMO (NF-kappa essential modulator, also known as IKK-gamma). The gene NEMO encodes a protein that regulates the function of various chemokines, cytokines, and adhesion molecules, and is essential for protection against tumor necrosis factor induced apoptosis, inflammatory, and immune response³.

• With this mutated gene, endothelial cells and other cells throughout the body can overexpress chemotactic factors specific for eosinophils, explaining why serum eosinophilia is common in IP patients.

• The epidermal skin lesions also show extensive involvement of eosinophils. It appears that the eosinophils, combined with other factors, lead to extensive inflammation, affecting not only the skin, but also endothelial cells.

• It is believed that ...