Dermcase: Brown warty plaques on an infant

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Diagnosis: Epidermal nevus syndromewith hemimegalencephaly

Cause

EN usually present at birth, or within the first few months of life, and follow the lines of Blaschko creating a pattern recognized as genetic mosaicism. Rarely, EN do not become clinically apparent until puberty.³ Although EN can involve any part of the body, the head and neck are the most commonly involved sites.⁴

Clinical presentation

Epidermal nevus syndrome

The term epidermal nevus syndrome (ENS) was coined by Solomon and Esterly in 1975, for the spectrum of clinical and histologic subtypes of EN associated with distinguishable genetic and systemic abnormalities. Several syndromes have been identified including: sebaceous nevus syndrome, nevus comedonicus syndrome, Becker nevus syndrome, phakomatosis pigmentokeratotica, congenital hemidysplasia with ichthyosiform nevus and limb defects (CHILD) syndrome, Proteus syndrome, inflammatory linear verrucous epidermal nevus (ILVEN) syndrome, and keratinocytic nevus syndrome.

Of those patients with EN, it is estimated that between 8% and 18% may have abnormalities in the ocular, neurologic, and musculoskeletal systems.¹ EN can also rarely be associated with abnormal cardiac and urogenital systems. The presence of one or more abnormalities is more likely in patients with widespread nevi than in patients with localized lesions.⁴ In a large series of sebaceous nevi, ocular and neurological abnormalities were commonly associated with large sebaceous nevi on the head.⁵

Of those patients with epidermal nevus syndrome, up to 50% demonstrate central nervous system (CNS) abnormalities.² These defects include seizures, mental retardation, and structural brain malformations including brain dysgenesis, cortical atrophy, microcephaly, hemimegalencephaly, ventriculomegaly, intracranial vascular malformations, hydrocephalus, and cranial nerve abnormalities.^2,3,6 Some studies have suggested that there is a correlation between nevi of large size or nevi involving the centrofacial area, and CNS abnormalities.^2,3,7,8 Baker et al suggested that CNS abnormalities were most often ipsilateral to the skin lesion, as seen in our patient.⁸

In 1991 Pavone et al identified a small subset of ENS patients with a neurological syndrome including facial epidermal nevus, ipsilateral hemimegalencephaly (HME), mental retardation, seizures, and ipsilateral facial hemihypertrophy.⁹ Hemimegalencephaly (HME) is a rare brain malformation that involves overgrowth of one hemisphere. Infants with ENS variant with HME often develop early onset of intractable epilepsy, and contralateral hemiparesis, as observed in our patient. Surgical treatment involves hemispherectomy or lobectomy. Approximately 60% of patients with ENS variant with HME become seizure-free after hemispherectomy.¹⁰