[PENS (papular epidermal nevus with "skyline" basal cell layer)]

Area of Science:

• Dermatology
• Neurology
• Genetics

Background:

• Papular Epidermal Nevus with "Skyline" Basal Cell Layer (PENS) is a rare neuro-cutaneous syndrome characterized by epidermal hamartomas and neurological anomalies.
• PENS is a type of keratinocytic epidermal hamartoma syndrome.

Observation:

• A 6-year-old boy presented with asymptomatic pigmented congenital plaques on his forehead and occipital region.
• Clinical examination revealed verrucous, light brown plaques with coalescent polygonal papules.
• Histopathological analysis confirmed acanthotic epidermis with basal hyperpigmentation, consistent with PENS.

Findings:

• The patient was diagnosed with PENS hamartoma, presenting with a unique association with autism spectrum disorder (ASD).
• Histopathology revealed a characteristic "skyline" arrangement of basal cell nuclei, though this feature is not always present.
• Neurological signs associated with PENS are typically non-specific, including developmental delays and epilepsy.

Implications:

• This case expands the clinical spectrum of PENS, highlighting its association with ASD.
• The findings support PENS as an autonomous neuro-cutaneous disorder within keratinocytic epidermal hamartoma syndromes.
• Further research is needed to understand the pathogenesis and full range of neurological associations in PENS.