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2026-09-29 | Nail Unit Involvement in a Porokeratosis-Spectrum Lesion Exhibiting Porokeratotic Adnexal Ostial Nevus-Like Features: Expanding the Clinical Spectrum.

Porokeratotic Adnexal Ostial Nevus (PAON) is an uncommon disorder characterized by abnormal keratinization affecting eccrine and follicular adnexa. Initially described separately as porokeratotic eccrine ostial and dermal duct nevus and porokeratotic eccrine and hair follicle nevus, the term PAON was introduced in 2009 to encompass these conditions. PAON presents with diverse clinical manifestations, ranging from asymptomatic keratotic papules and plaques to verrucous lesions. Typically appearing at birth, PAON can rarely manifest in adulthood. We report a case of a porokeratosis-spectrum lesion with features overlapping with PAON in a male patient in his 30s presenting with longitudinal splitting of the left thumbnail associated with an erythematous linear lesion extending from the nail matrix, alongside a scaly plaque on the proximal nail fold and dorsal thumb. This case highlights the importance of considering porokeratosis-spectrum disorders, including lesions with PAON-like features, in the differential diagnosis of monodactylous erythronychia and onychodystrophy, particularly due to its potential for subtle cutaneous involvement as was present in this case. This instance represents a rare presentation of a porokeratosis-spectrum lesion involving the nail unit epithelium and contributes to the expanding clinical spectrum of porokeratosis with PAON-like features.

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2025-08-27 | An Adult-Onset Case of Porokeratotic Eccrine Ostial and Dermal Duct Nevus (PEODDN) in a Previously Healthy 28-Year-Old Indian Male: A Case Report.

A 28-year-old Indian male with no previous medical or dermatological history presented with mildly pruritic linear skin lesions over the right anterior chest and arm. The lesions had been gradually progressing over the course of six years. Examination revealed multiple confluent, reddish-brown papules following Blaschko's lines, along with punctate hyperkeratotic papules over the right hand, with sparing of the mucosa, scalp, and nails. Histopathological analysis demonstrated a cup-shaped epidermal invagination filled with a parakeratotic column, absence of the granular layer, and dyskeratotic keratinocytes, with an eccrine duct located at the base of the lesion - indicating an acrosyringial origin. These findings confirmed the diagnosis of porokeratotic eccrine ostial and dermal duct nevus (PEODDN). PEODDN is a rare hamartomatous disorder with eccrine differentiation. While it usually presents at birth or during childhood, adult-onset cases have been documented - particularly along Blaschko's lines. The condition may present with porokeratotic plaques or comedo-like plugs on acral sites, and our case uniquely exhibited both features. Although its pathogenesis remains unclear, several theories suggest abnormal keratinization, structural defects in eccrine ducts, and possible genetic mutations. PEODDN may occasionally be associated with systemic or neoplastic conditions. Treatment options remain variable, and while no standard therapy offers complete resolution, our findings support the potential role of oral retinoids in improving lesion appearance and symptoms in adult-onset cases. Further evaluation of systemic retinoid therapy in PEODDN is warranted.

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2025-04-30 | Dermoscopy of a Rare Case of Porokeratotic Eccrine Ostial and Dermal Duct Nevus

PresentationA 20-year-old female presented with multiple asymptomatic raised lesions over the right hand since birth.Family history

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2024-10-30 | Porokeratotic eccrine and ostial dermal duct nevus

Porokeratotic eccrine ostial and dermal duct nevus (PEODDN) is a rare benign eccrine nevoid hamartoma with only a few cases reported till date. It is characterized by asymptomatic or mildly pruritic pitted comedone-like papules on palms or soles and keratotic papules and plaques in a linear pattern on the extremities, usually present in childhood. We present here three interesting cases of the same. Diagnosis was confirmed by histopathology which showed parakeratotic columns overlying mature eccrine sweat glands in dermis and dyskeratotic cells of lower epidermis.

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2016-04-16 | Topical Keratolytics for a Case of Porokeratotic Eccrine Ostial and Dermal Duct Nevus

Porokeratotic Eccrine Ostial and Dermal Duct Nevus (PEODDN) is a rare disorder of keratinization characterized by the presence of cornoid lamellae and association with eccrine sweat ducts. These lesions are usually benign and asymptomatic, so treatment is often for cosmetic purposes. Current therapies for PEODDN are either insufficient or impractical. We present a case of PEODDN treated with topical tretinoin 0.05% cream and 5-fluorouracil 5% cream with the hopes of providing an efficacious, financially relevant, and well-tolerated treatment regime for PEODDN. The combination of topical tretinoin and 5-fluorouracil did not provide substantial improvement in the lesions of a patient treated with this therapy for 6 weeks, and further studies are needed to identify an efficacious treatment for PEODDN that is both well-tolerated and economically feasible for patients with this condition.

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