Systematized linear porokeratosis: A rare variant of diffuse porokeratosis with good response to systemic acitretin

Porokeratoses: an update on pathogenesis and treatment

Porokeratoses (PK) are a group of uncommon dermatoses characterized by abnormal epidermal differentiation due to a disorder of the mevalonate metabolic pathway. Several clinical subtypes exist that can be associated with the same patient or affect different patients within a family and could, therefore, be different expressions of one disease. All PK subtypes share a common histopathologic finding, the cornoid lamella, a vertical stack of parakeratotic corneocytes embedded in an orthokeratotic horny layer. PK often affects immunosuppressed patients, in whom the course may parallel the level of immunosuppression. The pathogenesis of PK, which had long remained mysterious, has been recently unraveled after discovering pathogenic variants of genes involved in the mevalonate metabolic pathway. The disease is due to germline pathogenic variants of genes of this pathway but requires a second-hit event to manifest; therefore, PK is considered a dominantly inherited but recessively expressed condition. The prognosis of PK is usually favorable, even though the lesions progress to keratinocyte carcinomas in 7%-16% of patients. The treatment of PK was based on physical (ablative) procedures and various (topical or systemic) treatments, whose efficacy is nevertheless inconsistent and often temporary. The discovery of the metabolic pathway involved in the pathogenesis of PK paved the way for the elaboration of new topical treatments (combination of statins and cholesterol), which are more regularly efficacious compared with older treatments, even though the management of some patients with PK may still be challenging.

Porokeratoses-A Comprehensive Review on the Genetics and Metabolomics, Imaging Methods and Management of Common Clinical Variants

Porokeratosis is a heterogeneous group of keratinising disorders characterised by the presence of particular microscopic structural changes, namely the presence of the cornoid lamella. This structure develops as a consequence of a defective isoprenoid pathway, critical for cholesterol synthesis. Commonly recognised variants include disseminated superficial actinic porokeratosis, disseminated superficial porokeratosis, porokeratosis of Mibelli, palmoplantar porokeratosis (including porokeratosis palmaris et plantaris disseminata and punctate porokeratosis), linear porokeratosis, verrucous porokeratosis (also known as genitogluteal porokeratosis), follicular porokeratosis and porokeratoma. Apart from the clinical presentation and epidemiology of each variant listed, this review aims at providing up-to-date information on the precise genetic background, introduces imaging methods facilitating the diagnosis (conventional and ultraviolet-induced fluorescence dermatoscopy, reflectance confocal microscopy and pathology), discusses their oncogenic potential and reviews the literature data on the efficacy of the treatment used, including the drugs directly targeting the isoprenoid-mevalonate pathway.

[CME Dermatology 24: Porokeratosis]

CME Dermatology 24: Porokeratosis Abstract. Porokeratoses are a heterogeneous group of cornification disorders with the characteristic histological feature of the cornoid lamellae in the area of the marginal ridge. It is a rare but characteristic disease that occurs primarily in adulthood. Men are slightly more likely to be affected. The etiopathogenesis that leads to the transformation of the keratinocytes remains unclear; associations with genetic mutations and trigger factors such as UV rays and immunosuppression were observed. Due to the risk of malignant degeneration, consistent sun protection and regular clinical controls should take place. Cryotherapy, ablative laser therapy, curettage, photodynamic therapy or topical application of fluorouracil (5-FU), imiquimod and retinoids can be used to treat itchy, painful or cosmetically disturbing porokeratoses, depending on the location and severity.

Treatment of Porokeratosis: A Systematic Review

BACKGROUND

Porokeratosis (PK) is a rare skin disease of unknown etiology. It consists of a keratinization disorder, which may appear in several clinical forms and can undergo malignant transformation. The histopathological hallmark of PK is the cornoid lamella. While many topical, systemic, and surgical treatment modalities for PK have been described, no randomized controlled trials have been performed yet. Because of a lack of treatment standards for PK, European and international guidelines cannot be created.

OBJECTIVE

The aim of this systematic review is to outline options for treating PK.

METHODS

We performed a systematic literature search in an electronic database for published literature. A total of 88 articles fulfilling our inclusion criteria were found.

RESULTS

There were no randomized controlled trials on the treatment of PK, but mainly case reports and case series. Porokeratosis of Mibelli showed the best outcomes after treatment with imiquimod cream and linear PK responded well to topical or systemic retinoids. Topical vitamin D acid derivatives may be the best therapeutic option for disseminated PK. Surgical interventions and cryotherapy may be preferred in areas where the use of topical agents is difficult or contraindicated.

CONCLUSION

To offer patients with PK an evidence-based high-quality standardized therapy, randomized controlled trials are needed.

Efficacy of acitretin for porokeratosis in a child with chronic cutaneous graft versus host disease

Porokeratosis is a rare disorder of epidermal keratinization that is regarded as a precancerous. Recipients of hematopoietic stem cell transplantation (HSCT) have a greater risk of skin cancer; chronic graft versus host disease (GVHD) is an additional risk factor. A 16-year-old boy who had received HSCT for acute myelogenous leukemia was referred to us for sclerodermoid chronic cutaneous GVHD. Two years later, he developed disseminated porokeratosis with a few atypical lesions. Despite cryotherapy, numerous lesions of porokeratosis recurred rapidly. Acitretin resulted in good clinical response and reduced the rate of onset of new lesions.

Linear porokeratosis: a case report

Porokeratosis is a rare genodermatosis based on chronic keratinization disorder histologically characterized by the presence of a cornoid lamella and various clinical manifestations. Five most commonly described types of poroketarosis are porokeratosis of Mibelli or ”classic” porokeratosis, disseminated superfi cial actinic porokeratosis, disseminated palmoplantar porokeratosis, linear porokeratosis, and punctate porokeratosis. In all of the fi ve clinical types of porokeratosis described today, cases of planocellular skin carcinoma are described, except in punctate type cases. Use of topical CO2 laser ablation, cryotherapy and topical use of 5% Imiquimod cream, have shown favorable effects in local treatment of porokeratosis. The authors present a clinical case of a girl suffering from linear porokeratosis over the course of the last four years, spreading on the inside of her right arm along the lines of Blaschko. Linear porokeratosis was histologically confi rmed by biopsy of skin lesions and dermoscopy. Dermoscopic fi ndings, used as an auxiliary method, also indicated linear porokeratosis. Successful liquid nitrogen cryotherapy prompted the authors to present a case in which the applied treatment proved to be successful, but also to emphasize the need for timely treatment in order to prevent malignant alterations of these changes.

Facial follicular porokeratosis: a case report

Porokeratosis is a disorder of keratinization, characterized clinically by a peripheral keratotic ridge and histologically by the cornoid lamella. We describe a patient with follicular porokeratosis with a distinctive clinical presentation. We believe that follicular porokeratosis is a unique histopathologic variant of porokeratosis, with cornoid lamellae centered in follicular infundibula. Further, this is the only report of follicular porokeratosis involving the face exclusively.