Epidermal Nevus Syndrome Workup

Updated: Apr 18, 2019
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: William D James, MD  more...
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Workup

Imaging Studies

MRIs can be used to evaluate intracranial involvement. MRIs may show cerebral atrophy, dilated ventricles, hemimegalencephaly, pachygyria, or enlarged white matter.

Multiple abnormalities are found on neuroimaging studies in patients with Jadassohn nevus phacomatosis. Findings include hemimegalencephaly (usually ipsilateral to the major skin lesions and contralateral to neurologic deficits), cortical atrophy, pachygyria, cortical heterotopias, agenesis of the corpus callosum, and Dandy-Walker syndrome.

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Other Tests

EEG findings are abnormal in approximately 90% of patients. In almost all patients who had focal paroxysmal electroencephalographic abnormalities, the epileptiform focus was ipsilateral to the major skin lesions.

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Histologic Findings

Histologic examination of the four types of epidermal nevi is variable.

Typically, the histologic examination of linear epidermal nevus reveals marked hyperkeratosis, papillomatosis, and acanthosis with rete ridge elongation in a psoriasiform pattern. Changes of epidermolytic hyperkeratosis, acantholytic dyskeratosis, and those resembling verruca vulgaris and comedo formation may also be observed.

Histologic examination of inflammatory linear verrucous epidermal nevus reveals a similar psoriasiform hyperplasia of the epidermis, alternating parakeratosis without a granular layer, and orthokeratosis with a thickened granular layer. Occasionally, changes of epidermolytic hyperkeratosis, acantholytic dyskeratosis, and those resembling verruca vulgaris and comedo formation may be noted.

In nevus comedonicus, rudimentary hair follicles are dilated to form epidermal invaginations, which are filled with keratin in concentric lamellae. The follicular walls are composed of several layers of keratinocytes, which occasionally show changes of epidermolytic hyperkeratosis. Scattered hair shafts and small sebaceous lobes may be evident in early specimens; in older specimens, the shafts and lobes, as well as arrector pili muscles, are absent. The interfollicular epidermis is often papillomatous and hyperkeratotic, and ossification may be observed in the dermis.

Linear sebaceous nevus combines epidermal, follicular, sebaceous, and apocrine gland abnormalities. It reflects the normal sebaceous elements seen in infancy, childhood, and adolescence. Thus, in early life, the lesions are well developed because of maternal hormonal expression, whereas, in childhood, they are underdeveloped and reduced in size and number. At this stage, incomplete and undifferentiated hair structures may be a key to diagnosis, with prominent keratin-filled infundibula and malformed hair germs.

At puberty, this neoplasm tends to blossom with large, maturing sebaceous glands and papillomatous hyperplasia. In adulthood, benign appendageal tumors as well as malignant ones may develop. Syringocystadenoma papilliferum, chondroid syringoma, and nodular hidradenoma are most common in infancy. Basal cell carcinoma, squamous cell carcinoma, or keratoacanthoma are most common in adulthood. Rarely, tumors, such as apocrine carcinoma and porocarcinoma, may appear with more metastatic potential.

One series of 155 cases of linear sebaceous nevus with clinicopathologic correlation could not identify any cases of authentic basal cell carcinoma or other malignancies, whereas several examples of primitive follicular induction and trichoblastomas were evident. [35] Other cutaneous hamartomas, hyperplasias, and neoplasms in that series included sebomatricoma, apocrine gland cyst, poroma, and different histopathologic variants of what are often considered to be warts (eg, classic warts, tricholemmoma, desmoplastic tricholemmoma).

Neuropathologic findings may also be evident. Nervous system changes may also occur in patients with linear epidermal nevus syndrome. Disorganization of cortical neuronal migration and organization, polymicrogyria, heterotopia, white matter gliosis, increased neuronal size, and/or excessive neuron and astrocyte proliferation may be observed.

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