INTRODUCTION
Porokeratosis is a disorder of epidermal keratinization that encompasses multiple clinical variants based on different patterns of distribution. It classically manifests as one or more erythematous, annular plaques with an atrophic center and hyperkeratotic ridge-like border.1-3 The primary lesion of classic porokeratosis starts as a small, light brown, scaly papule that spreads in a centrifugal manner and may slowly progress and coalesce into a sharply circumscribed plaque of various sizes and forms.4,5 The lesions are often asymptomatic but may be associated with pruritus.1
Porokeratosis lesions may affect any part of the body, including palmoplantar surfaces and mucous membranes, but are more prevalent on the trunk and extremities.1,2 Porokeratosis may be classified as classic porokeratosis of Mibelli, linear porokeratosis, disseminated porokeratosis, disseminated superficial actinic porokeratosis, punctuate porokeratosis, or porokeratosis palmaris et plantaris disseminata.1,3 The histopathological hallmark of porokeratosis is the cornoid lamella, characterized by a thin column of parakeratotic corneocytes embedded within the stratum corneum, forming an indentation within the epidermis.1,3,4 While the exact pathogenesis of porokeratosis remains unclear, it may be acquired or hereditary, and is thought to be due to the clonal expansion of abnormal epidermal keratinocytes.1,4 The proliferation of abnormal clones may be triggered by extrinsic factors such as irradiation, infective agents, mechanical trauma, and immunosuppression.1 The differential diagnosis of porokeratosis includes actinic keratosis, seborrheic keratosis, psoriasis, lichen planus, Bowen’s disease, and squamous cell carcinoma.2,4
The overall prognosis of porokeratosis is favorable. However, a potential complication is an increased risk (estimated to be less than 10%) of malignant transformation of a porokeratosis lesion to a basal or squamous cell carcinoma.1,6 Risk factors include large lesion size, localization on the extremities, older age, and a long period of existence.1
There is no definitive or “gold standard” treatment regimen for porokeratosis, and current therapeutic approaches have variable efficacy and durability. Asymptomatic lesions are often managed conservatively with sun protection, emollients, and clinical surveillance for signs of malignant degeneration.1 Current therapeutic modalities used to improve the signs and symptoms of porokeratosis include many topical, systemic, and surgical treatment options such as: 5-fluorouracil cream, topical vitamin D3 analogs, topical and systemic retinoids (eg, acitretin or isotretinoin), cryotherapy, dermabrasion, laser ablation, imiquimod, ingenol mebutate, topical diclofenac, cantharidin, corticosteroids, topical tacrolimus, phototherapy, and surgical excision.3,4 A systematic review found that no randomized controlled trials have been conducted to assess treatments
Porokeratosis lesions may affect any part of the body, including palmoplantar surfaces and mucous membranes, but are more prevalent on the trunk and extremities.1,2 Porokeratosis may be classified as classic porokeratosis of Mibelli, linear porokeratosis, disseminated porokeratosis, disseminated superficial actinic porokeratosis, punctuate porokeratosis, or porokeratosis palmaris et plantaris disseminata.1,3 The histopathological hallmark of porokeratosis is the cornoid lamella, characterized by a thin column of parakeratotic corneocytes embedded within the stratum corneum, forming an indentation within the epidermis.1,3,4 While the exact pathogenesis of porokeratosis remains unclear, it may be acquired or hereditary, and is thought to be due to the clonal expansion of abnormal epidermal keratinocytes.1,4 The proliferation of abnormal clones may be triggered by extrinsic factors such as irradiation, infective agents, mechanical trauma, and immunosuppression.1 The differential diagnosis of porokeratosis includes actinic keratosis, seborrheic keratosis, psoriasis, lichen planus, Bowen’s disease, and squamous cell carcinoma.2,4
The overall prognosis of porokeratosis is favorable. However, a potential complication is an increased risk (estimated to be less than 10%) of malignant transformation of a porokeratosis lesion to a basal or squamous cell carcinoma.1,6 Risk factors include large lesion size, localization on the extremities, older age, and a long period of existence.1
There is no definitive or “gold standard” treatment regimen for porokeratosis, and current therapeutic approaches have variable efficacy and durability. Asymptomatic lesions are often managed conservatively with sun protection, emollients, and clinical surveillance for signs of malignant degeneration.1 Current therapeutic modalities used to improve the signs and symptoms of porokeratosis include many topical, systemic, and surgical treatment options such as: 5-fluorouracil cream, topical vitamin D3 analogs, topical and systemic retinoids (eg, acitretin or isotretinoin), cryotherapy, dermabrasion, laser ablation, imiquimod, ingenol mebutate, topical diclofenac, cantharidin, corticosteroids, topical tacrolimus, phototherapy, and surgical excision.3,4 A systematic review found that no randomized controlled trials have been conducted to assess treatments
