JRSM >
Volume 96, Number 1 >
Pp. 30-31
Department of Dermatology, Frimley Park Hospital, Frimley, Camberley GU16
5UJ, London, UK
1 Department of Dermatology, St George's Hospital, London, UK
2 Department of Paediatric Dermatology, Great Ormond Street Hospital, London,
UK
Correspondence to: Dr Virginia A Hill
We report a 5-year-old girl with a rare and unusual variant of the epidermal naevus syndrome. There are a handful of cases previously reported.
CASE HISTORY
The patient was born at 36 weeks' gestation after a pregnancy complicated by pre-eclampsia, weighing 2.5 kg. At birth she was noted to have three pigmented lesions on the right forearm and a warty lesion on the right little finger. At 10 days of age erythema appeared on the right abdomen, arm and leg which gradually darkened and became slightly raised. A lentiginous area with raised pigmented lesions also appeared on the upper back. By the age of 18 months the pigmented lesions on the back, arm and hand had gradually extended. There was also an extensive epidermal naevus on the right of the body (Figure 1). The pigmented lesions on the upper back and the epidermal naevus on the lower back crossed the midline.
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By the age of four years there were large melanocytic naevi in a speckled lentiginous pattern on the upper back, forearm and hand, composed of papules and nodules, some of which were reddish in colour. The epidermal naevus had sebaceous features and involved the right abdomen, arm and leg down to the foot. The configuration was in keeping with Blaschko's lines1. On the medial aspect of the wrist the epidermal naevus coexisted with melanocytic naevus (Figure 2).
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The child has severe epilepsy, which began as apnoeic attacks at the age of nine days and then manifested as ‘absences’, drop attacks, floppy episodes and partial complex seizures which can occur several times daily. She has been treated with sodium valproate, carbamazepine, lamotrigine and more recently carbamazepine with diazepam, all of which have been helpful. In addition, a mild right hemiparesis and developmental delay were diagnosed at the age of four months, both of which have virtually resolved. Investigations, including repeated electroencephalograms, video-telemetry, electrocardiogram, hearing test and chromosome analysis, were all normal. A recent MRI brain scan did show some enlargement of the left lateral ventricle, but this is not thought to be significant.
On histological examination, a skin biopsy from the right side of the abdomen revealed hyperkeratosis, papillomatosis and acanthosis. There were scattered mature sebaceous glands, hair follicles and eccrine glands in the epidermis, in keeping with a verrucous epidermal naevus with prominent sebaceous differentiation. Several pigmented lesions have been removed and proved to be benign melanocytic naevi, some with features of Spitz naevi.
Management has included surgical excision of some of the raised pigmented lesions on the right hand. Two laser treatments have been undertaken under general anaesthesia. Several of the pigmented lesions have been removed from the back and hand with the carbon dioxide laser, with variable results; some have already recurred but in other areas the cosmetic result is good. A test treatment on the epidermal naevus showed about 40% improvement but the parents decided against treatment of such a large area. The possible risk of malignant change within the pigmented areas is a concern.
COMMENT
The epidermal naevus syndrome is the combination of a widespread epidermal naevus and other associated features including skeletal, neurological, eye and cardiac defects, developmental delay and precocious puberty. There are associated cutaneous abnormalities in at least one-third of patients: examples are woolly hair naevus2, naevus comedonicus, café-au-lait spots, hypopigmented patches, haemangiomas and melanocytic naevi.
Phacomatosis pigmentokeratotica is a rare and distinct variant of the epidermal naevus syndrome, first described by Happle et al.3. It comprises the association of an organoid (epidermal) naevus with sebaceous differentiation and a speckled lentiginous naevus4,5 arranged in a checkerboard pattern. There are often other anomalies, most commonly neurological or skeletal, such as hemiatrophy, dysaesthesia and hyperhidrosis in a segmental pattern, mild mental retardation, seizures, deafness, ptosis and strabismus6.
The hypothesis of ‘twin-spotting’ has been proposed by Happle et al. to explain the coexistence of two separate and distinct naevi6 in a segmental pattern, involving adjacent or corresponding regions of the body. Twin-spotting has been studied in plants, as well as in Drosophila melanogaster, and is based on the concept of somatic recombination due to an early post-zygotic mutational event. Two different autosomal recessive mutations must be located on the same chromosome pair, one on each homologous chromosome. The embryo is therefore double heterozygous. In early embryogenesis post-zygotic crossing-over and recombination results in two different homozygous populations of cells forming separate mosaic patterns. Another example of a similar process is phacomatosis pigmentovascularis—the combination of a widespread telangiectatic naevus and an extensive pigmentary naevus7 which was described by Happle et al. before phacomatosis pigmentokeratotica.
Only a few cases of phacomatosis pigmentokeratotica have been recorded and we hope that other clinicians will recognize this unusual condition. There is a small but definite risk of malignant change within the pigmented lesions and the epidermal naevus in later life. Internal malignancies have been reported in the epidermal naevus syndrome, but none in phacomatosis pigmentokeratotica.
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years: epidermal naevus right side of trunk and leg, with
coexistence of epidermal naevus and melanocytic naevus right hand