Porokeratosis is one of the most common genodermatoses and is associated with an increased risk of keratinocyte cancer and melanoma.

BACKGROUND: Porokeratosis is a clinically heterogeneous group of keratinization disorders with a genetic background mainly affecting the mevalonate pathway, which is involved in the synthesis of cholesterol, an essential component for the formation of the extracellular lipid lamellae in the stratum corneum. Porokeratosis is reportedly associated with an increased risk of keratinocyte cancer, but to date, no large epidemiological studies have been conducted to further address this association. OBJECTIVES: The first objective was to characterize a cohort of patients diagnosed with porokeratosis at the Department of Dermatology and Venereology, Sahlgrenska University Hospital (SU), Gothenburg, Sweden. The second objective was to conduct a nationwide registry-based cohort study to investigate the association, if any, between porokeratosis and the cutaneous malignancies squamous cell carcinoma (SCC), basal cell carcinoma (BCC) and melanoma. METHODS: For the SU cohort, the hospital registry was searched for patients with a diagnosis of porokeratosis recorded between 2016 and 2020. Clinical data were extracted from the records of the identified patients. For the nationwide cohort, national registries were searched to identify patients with a diagnosis of porokeratosis between 2001 and 2020. A tenfold control cohort was formed by Statistics Sweden. The data was cross-referenced with the Swedish Cancer Register to study the associations between porokeratosis and SCC, BCC and melanoma. RESULTS: Disseminated superficial actinic porokeratosis was the most common clinical type among the 108 patients in the SU cohort. In the nationwide search, 2277 patients with porokeratosis were identified (prevalence 1/4132). Porokeratosis was associated with an increased risk for SCC, BCC and melanoma with hazard ratios (95% CI) of 4.3 (3.4-5.4), 2.42 (1.97-2.98) and 1.83 (1.18-2.82), respectively, in the patient cohort, compared to the matched control group. CONCLUSION: Porokeratosis is a common genodermatosis, and it is associated with an enhanced risk of skin cancer.

Eruptive pruritic papular porokeratosis or inflammatory form of disseminated superficial porokeratosis: a new case and review of the literature.

Porokeratosis is a heterogeneous group of dermatoses with alterations of keratinization. Histologically, they are characterized by the presence of cornoid lamellae. Eruptive pruritic papular porokeratosis (EPPP) or the inflammatory form of disseminated superficial porokeratosis (or eruptive disseminated porokeratosis) is an infrequent variant, characterized by pruritic erythematous papules or annular lesions. We present a 72-year-old woman with EPPP, exhibited by pruritic lesions on the extremities and back, and review the literature concerning this condition. We found 32 cases of EPPP or inflammatory disseminated superficial porokeratosis (including the current case) reported in the literature, with a median age of 66 years (range, 13-84); 59.3% were men. Eruptive pruritic papular porokeratosis was associated with various neoplasms in 31.2% of cases. Six patients had an associated viral infection. Response to treatment was poor in most cases. Eruptive pruritic papular porokeratosis resolved spontaneously in 75% of cases. Median time to resolution was 6 months (range, 1-24). Eruptive pruritic papular porokeratosis (or inflammatory disseminated superficial porokeratosis/eruptive disseminated porokeratosis) is an infrequent variant of porokeratosis characterized by intense pruritus and spontaneous resolution in most individuals. Eruptive pruritic papular porokeratosis can be associated with neoplasms and screening for malignancies is recommended if clinically indicated.

Lichenoid inflammation of DSAP lesions following treatment with durvalumab, olaparib and paclitaxel: A potential diagnostic pitfall mimicking lichenoid drug eruptions associated with PDL-1 inhibitors.

Disseminated superficial actinic porokeratosis (DSAP) is an uncommon skin condition that can be inherited or may occur sporadically with multiple red-brown, thin plaques in a photodistribution. The condition more often affects middle-aged women and is often recalcitrant to therapy. In rare literature reports, systemic medications can trigger exacerbation or promote inflammation in pre-existing lesions of DSAP. We present a novel case of chemotherapy-associated DSAP inflammation in a 66-year-old woman after triple therapy with durvalumab (PD-L1 inhibitor), olaparib (PARP inhibitor) and paclitaxel, showing similarities to primary lichen planus-like eruption from immune checkpoint inhibitors.

Linear porokeratosis associated with Bardet-Biedl syndrome: A case report.

This case report presents a 17-year-old boy with Bardet-Biedl syndrome (BBS) and a long-standing hyperpigmented eruption on the left trunk and upper extremity, clinically and histologically consistent with linear porokeratosis (LP). BBS patients frequently require solid organ transplant, and subsequent immunosuppression places them at especially high risk for malignant transformation of premalignant skin lesions such as LP. Although BBS affects multiple organ systems, there are only a handful of case reports detailing associated cutaneous involvement, and, to our knowledge, this is the first reported case of linear porokeratosis occurring in patient with BBS.

An unusual spiculated presentation of follicular porokeratosis.

Follicular porokeratosis is a rare variant of porokeratosis in which the coronoid lamellae are confined to hair follicles. It classically presents with annular plaques with a surrounding keratotic ridge. However, the clinical presentation has shown significant variation in reported cases. We present the case of a 26-year-old man with chronic diffuse follicular spicules associated with alopecia. Clinical findings were suggestive of trichodysplasia spinulosa, but multiple biopsies showed findings consistent with follicular porokeratosis. Diffusely spiculated presentation as present in our patient has not been previously reported in the literature. It is important to recognize the necessity of histopathologic confirmation in a diagnostically challenging condition such as follicular porokeratosis.

Genitogluteal porokeratosis in an HIV-positive man: a case report and review of the literature on genital porokeratosis.

Genitogluteal porokeratosis is a disorder of keratinization that may present in men in their fourth decade of life. We describe a 52-year-old human immunodeficiency virus (HIV)-positive man with history of anal squamous cell carcinoma who developed verrucous lesions on the buttocks and genitals. The buttock lesions presented shortly after radiotherapy for anal carcinoma a decade prior, whereas the genital lesions presented three months prior in areas treated with injectable medication for erectile dysfunction. Skin biopsy revealed a cornoid lamella, leading to the diagnosis of genitogluteal porokeratosis. The buttock lesions were treated with shave excision and the genital lesions were treated with topical agents. Using the PubMed database, a literature search was performed with combinations of the following key words: acuminata, condyloma, cornoid lamella, genital, genitogluteal, HIV, penile, porokeratosis, verrucous, vulvar. The generated papers and their references were reviewed. To the best of our knowledge, we present the first reported case of genitogluteal porokeratosis in an HIV-positive man. Notably, these lesions developed in sites of prior radiation or injection. This condition should be included in the differential diagnosis of chronic lesions of the genitals and buttocks in patients with HIV and/or history of radiation treatment and/or trauma to the genitogluteal region.

A report and follow up of a patient with disseminated superficial actinic porokeratosis (DSAP) undergoing novel systemic treatment with palifermin (a keratinocyte growth factor) during chemotherapy.

Disseminated superficial actinic porokeratosis (DSAP) is an inherited dermatosis triggered by chronic ultraviolet light exposure. Cosmetic improvement has been noted with topical therapies or laser treatment. Lesions of DSAP are precancerous, having been reported to develop into squamous cell carcinomas (SCCs) or basal cell carcinomas (BCCs) occasionally. We describe a patient with longstanding DSAP who developed a primary CNS lymphoma. Palifermin (a keratinocyte growth factor analogue) was used as an adjuvant for his chemotherapy to minimize mucositis. Our patient noted marked clinical improvement of his DSAP following his chemotherapy for lymphoma. Follow-up has shown a sustained improvement of his DSAP with no development of any SCCs. Palifermin may be safe for use in individuals at high risk of developing SCCs and further research into keratinocyte growth factors and risk of development of SCC is warranted. Systemic chemotherapy appears to improve DSAP lesions.

Porokeratosis ptychotropica responding to photodynamic therapy: An alternative treatment for a refractory disease.

BACKGROUND: Porokeratosis ptychotropica (PP) is a rare variant of porokeratosis with a special predisposition to affect body folds, particularly the intergluteal cleft. This disease is resistant to most topical and systemic treatments, as shown in the review of the literature we provide here. Itching and discomfort are often a difficult problem to solve. PATIENTS AND METHODS: Two patients with PP that had not responded to multiple topical treatments were treated with photodynamic therapy (PDT). Changes in plaque size, thickness and symptoms were assessed after treatment. RESULTS: Pruritus disappearance was observed in both patients after treatment with PDT. Partial clearance of the plaques was observed in one case. In the other case, a moderate clearance of hyperkeratosis was observed, although the size of the lesions persisted unchanged. CONCLUSIONS: PDT seems to be a good therapeutic alternative in the treatment of PP, as it can provide symptomatic relief and clinical improvement of the lesions. However, it does not appear to be a curative treatment. Moreover, long-term response is still unknown.

Follicular porokeratosis: four new cases.

Porokeratosis, a disorder of keratinisation, is clinically characterized by the presence of annular plaques with a surrounding keratotic ridge. Clinical variants include linear, disseminated superficial actinic, verrucous/hypertrophic, disseminated eruptive, palmoplantar and porokeratosis of Mibelli (one or two typical plaques with atrophic centre and guttered keratotic rim). All of these subtypes share the histological feature of a cornoid lamella, characterized by a column of 'stacked' parakeratosis with focal absence of the granular layer, and dysmaturation (prematurely keratinised cells in the upper spinous layer). In recent years, a proposed new subtype, follicular porokeratosis (FP_, has been described, in which the cornoid lamella are exclusively located in the follicular ostia. We present four new cases that showed typical histological features of FP.

Porokeratotic Adnexal Ostial Nevus-Report of a Case With Unusual Clinical and Histologic Features.

An 11-year-old Tanzanian girl presented with diffuse verrucous lesions of varying morphology, scarring alopecia, and keloid scars over the face with a predilection for the ears. Physical examination revealed dark keratoderma and patches of hypopigmentation near the midline of the dorsal trunk (Figure 1a). Her forearms were densely covered by verrucous lesions with the exception of a clear linear patch on the dorsal aspect of the left forearm (Figure 1b). The perioral area was notable for white spires projecting from verrucous papules (Figure 1c) while the oral mucosa and teeth appeared normal on visual examination. The rest of her body, including the palms and soles, was covered by patchy, scaly lesions of varying severity.

Hyperkeratotic variant of porokeratosis in a patient with Hepatitis C virus infection and a concomitant immunosuppressed state.

Porokeratoses are acquired and hereditary disorders of keratinization that share a distinctive lesion characterized by raised keratotic borders corresponding histologically to an angled column of parakeratotic cells, called a cornoid lamella. Although a precise mechanistic explanation is lacking, ultraviolet radiation and immunosuppressed states are considered causally-associated with most cases of acquired porokeratosis. Hepatitis C virus (HCV) infection has been proposed as a link between the immunosuppressed states and development of acquired porokeratosis. Among the various recognized clinical entities that constitute this group, rare cases of hyperkeratotic variants have been described that may pose a diagnostic challenge. Herein we describe a remarkable case of the hyperkeratotic variant of porokeratosis that occurred in a patient with known HIV and HCV infections and a coexisting therapy-related immunosuppressed state. We also provide a review of the relevant literature.

Adult onset unilateral systematized porokeratotic eccrine ostial and dermal duct nevus: a case report.

Porokeratotic eccrine ostial and dermal duct nevus (PEODDN) is an uncommon, benign dermatosis that is characterized by asymptomatic grouped keratotic papules and plaques with a linear pattern on the extremities with distinct porokeratotic histopathological features. The lesions usually appear at birth or in childhood, although rare cases of late-onset adult PEODDN have been described. Herein we report a case of adult onset PEODDN with unilateral and segmental involvement.

Co-existence of porokeratosis variants concurrent with Bowen's disease: two rare cases report.

Coexisting variants of porokeratosis rarely occurs. Disseminated superficial porokeratosis (DSP) is characterized by multiple uniform small annular papules distributed all over body. DSP commonly coexist with linear porokeratosis (LP), but it is uncommon for DSP to coexist with porokeratosis of Mibelli (PM). PM presents with central atrophic erythematous plaques and thread-like elevated border. It occurs mainly on extremities. Although malignant transformation can be found in the porokeratosis, there is still no report case of coexisting variants of porokeratosis concurrent with Bowen's disease. The clinical and histopathologic finding of rare coexisting variants of porokeratosis (PM and DSP) concurrent with squamous dysplasia is described.

Porokeratotic eccrine ostial and dermal duct nevus - revisited.

We hereby report a rare case of a 14-year-old girl presenting with asymptomatic pitted papules over the flexor aspect of her right 4th and 5th digits. This was histopathologically proven to be porokeratotic eccrine ostial and dermal duct nevus (PEODDN).

Coexistence of congenital linear porokeratosis and disseminated superficial porokeratosis.

The coexistence of two or more forms of porokeratosis in a single individual is rarely reported. We report here on a patient exhibiting the coexistence of congenital linear porokeratosis and disseminated superficial porokeratosis. To our knowledge, this entity has been previously reported only once.