Porokeratotic Eccrine Ostial and Dermal Duct Nevus: A Report of Rare Late-Onset Solitary Lesion.

Porokeratotic eccrine ostial and dermal duct nevus (PEODDN) is a rare dermatological disorder with fewer than 100 reported cases. It is characterized by abnormal keratinization over the dilated acrosyringium, and is hypothesized to involve somatic mosaicism of the GJB2 gene. Typically presenting in early childhood with linearly distributed hyperkeratotic papules along the Blaschko line, PEODDN predominantly affects palms and soles. We report an atypical case of PEODDN in a 64-year-old woman who presented with an asymptomatic solitary nodule on her left foot that had been present for three months. Histopathological examination confirmed the diagnosis and revealed a characteristic cornoid lamella overlying the dilated acrosyringium. The lesion was successfully treated with a CO₂ laser, with complete resolution and no recurrence at one-month follow-up. This case highlights the importance of considering PEODDN in the differential diagnosis of solitary lesion in atypical locations, even in older adults, and contributes to the limited literature on the late-onset solitary presentation of this rare condition. Our comprehensive review of the literature provides insights into the pathogenesis, clinical variations, associated conditions, and treatment options of PEODDN, with the aim of guiding clinicians in managing this uncommon entity.