Papular epidermal nevus with "skyline" basal cell layer syndrome (PENS) is a very rare type of
keratinocytic epidermal nevi that includes a specific type of skin lesion and can be associated with other birth defects and neurological problems. The skin lesions appear as small, slightly scaly, pimples (papules) made of the thickened outer layer of the skin (hyperkerotosis) with a rough, ﬂat surface. The skin lesions may be visible at birth or soon after birth. There may be one lesion or multiple lesions anywhere on the body. The color of the skin lesions varies from white to brown and the shape may vary as well. Neurological symptoms, such as mild intellectual disability, seizures, and delayed development of mental and movement abilities (psychomotor delay), are present in
about 50% of the cases. Psychomotor delay may appear as clumsiness or difficulty playing sports. Deafness, unusual facial features, and genital birth defects, such as hypospadius or a curved penis, have been described in a few cases.
The diagnosis of PENS may be confirmed by a biopsy of the skin lesion and/or examination of the skin lesion and surrounding skin under a special microscope (dermoscopy). When there are four or more skin lesions, examination for neurological symptoms may be suggested. The cause of the PENS is not known, but there are several cases where more than one member of a family is affected. Treatment depends on the associated problems and may include surgery to correct genital birth defects, anti-seizure medication, and early intervention or extra help in school. In all presently described cases, the skin lesions have remained stable and benign and have not required treatment. When present, the neurological symptoms do not appear progressive, and in several cases, the seizures and psychomotor delays improved with age.
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Luna PC, Pannizardi AA, Martin CI, Vigovich F, Casas JG & Larralde M. Papular Epidermal Nevus with Skyline Basal Cell Layer (PENS): Three New Cases and Review of the Literature. Pediatr Dermatol. May, 2016; 33(3):296-300. https://www.ncbi.nlm.nih.gov/pubmed/26939784.
Rodríguez-Díaz E, Gonzalvo P, Colmenero I, Requena L, Hernández-Martín A, Torrelo A. Papular epidermal nevus with "skyline" basal cell layer (PENS) with extracutaneous findings. Pediatr Dermatol. July, 2013; 30(4):e54-6. https://www.ncbi.nlm.nih.gov/pubmed/22985090.