Squamous cell carcinoma arising from lesions of porokeratosis palmaris et plantaris disseminata

We report a 63-year-old Japanese man with numerous hyperkeratotic papules of porokeratosis palmaris et plantaris disseminata (PPPD) who developed multiple squamous cell carcinomas on the lesional sites of the palms and soles. The hyperkeratotic papules, which showed tightly packed columns of parakeratotic cells in the cornified layer (cornoid lamella), lost granular layer, and dyskeratotic keratinocytes in the epidermis below the cornoid lamella histologically, had been noticed on the palms and soles from the age of 28 and 43, respectively. He has no family history of such hyperkeratotic papules. Treatment with etretinate (10-50 mg/day) was given discontinuously, and the total dose of etretinate amounted to approximately 21 g over 14 years (average: 0.07 mg/kg/day). He noticed erosions on the hyperkeratotic papules on the left sole and palm more than 9 months after cessation of treatment with etretinate. Histological findings showed numerous atypical keratinocytes in the epidermis and upper dermis with mononuclear cell infiltration seen in the upper dermis. The diagnosis of squamous cell carcinoma arising from the lesions of porokeratosis palmaris et plantaris was made. Five erosions with histologically malignant changes were removed 1 cm from the margin of the erosions. These findings suggest that etretinate may have an inhibitory action on malignant changes in PPPD.     

Linear porokeratosis: a case report and review of the literature

Linear porokeratosis refers to 1 of 5 variants of porokeratosis. Porokeratosis is a keratinization disorder of multiple etiologies including genetic aberrancy, trauma, and infection. We review a case of a 35-year-old man with a chronic history of linear porokeratosis and conduct a review of porokeratosis subtypes, etiology, histology, pathology, differential diagnosis, and treatment.     

Giant porokeratosis

Porokeratosis is a disorder of keratinization characterized by annular plaques with an atrophic center surrounded by a raised, keratotic wall. It has several clinical forms including a porokeratosis of Mibelli, giant porokeratosis, linear porokeratosis, disseminated superficial actinic porokeratosis, palmoplantar porokeratosis and punctate porokeratosis. We report a patient with the rare condition of giant porokeratosis. Several variants of porokeratosis coexist in our patient.     

Linear porokeratosis with multiple squamous cell carcinomas successfully treated by electrochemotherapy

Porokeratosis is a clonal epidermal disorder of keratinization characterized by annular lesions with an atrophic centre and a hyperkeratotic edge. The cornoid lamella is the histopathological hallmark. Six clinical variants are recognized: porokeratosis of Mibelli; disseminated superficial porokeratosis; disseminated superficial actinic porokeratosis (DSAP); porokeratosis plantaris et palmaris disseminata; punctate porokeratosis and linear porokeratosis. Linear porokeratosis is the type most frequently associated with malignant transformation into squamous cell carcinoma (SCC). It is thought to represent a mosaic form of DSAP and has an incidence of less than 1 in 200 000; treatment options are limited. We describe a patient with systematized linear porokeratosis and multiple SCCs who was successfully treated with bleomycin electrochemotherapy (ECT), a form of intralesional chemotherapy. In view of their large number, the individual SCCs were treated with bleomycin ECT. One year post‐treatment the patient remains tumour free. To our knowledge, this is the first case of multiple SCCs treated by ECT in the context of systematized linear porokeratosis. Our case highlights the challenges associated with diagnosing and managing this unusual form of porokeratosis.     

Linear porokeratosis superimposed on disseminated superficial actinic porokeratosis: report of two cases exemplifying the concept of type 2 segmental manifestation of autosomal dominant skin disorders.

A concept of dichotomous types of segmental involvement of autosomal dominant skin disorders has recently been proposed. Among the different types of porokeratosis, disseminated superficial actinic porokeratosis is known to be an autosomal dominant skin disorder, and linear porokeratosis represents the segmental form of the disease. We intended to exemplify the type 2 segmental manifestation within this concept. Clinical and histopathologic aspects of porokeratotic lesions of 2 patients were investigated. The family history was studied in both cases. Linear porokeratosis superimposed on disseminated superficial actinic porokeratosis was observed in both patients. These 2 cases of linear porokeratosis associated with disseminated superficial actinic porokeratosis can be taken as further examples of a type 2 segmental involvement occurring in an autosomal dominant skin disorder.     

Disseminated superficial actinic porokeratosis. Coexistence with other porokeratotic variants

The coexistence of disseminated superficial actinic porokeratosis (DSAP) with other variants of porokeratosis is rare. We report three such cases: DSAP with porokeratosis of Mibelli; DSAP with linear porokeratosis; and DSAP occurring in the mother of a girl with linear porokeratosis. Although different areas of skin and different family members usually express the same morphological variant, we suggest that the simultaneous expression of two closely linked gene loci could explain the coexistence of different porokeratotic variants.     

Linear Porokeratosis in Two Families with Disseminated Superficial Actinic Porokeratosis

Two case reports of linear porokeratosis occurring in individuals or families with disseminated, superficial, actinic porokeratosis (DSAP) are presented. Linear porokeratosis and DSAP may be different expressions of one dominantly inherited condition. We reviewed the clinical features of linear porokeratosis and its association with other forms of porokeratosis. The linear form has a potential for carcinomatous change.     

Porokeratosis on the scrotum: two cases

Porokeratosis is a group of hereditary or acquired disorders of epidermal keratinization, characterized by keratotic lesions with an atrophic center and a prominent peripheral ridge. At least seven clinical variants have been identified: the plaque type, disseminated superficial porokeratosis, disseminated superficial actinic porokeratosis, linear porokeratosis, giant porokeratosis, porokeratosis plantaris palmaris et disseminate, and punctuate porokeratosis. Genital porokeratosis is a rare condition even in disseminated forms. We described two male patients who had porokeratosis only affecting the scrotum. The patients were treated by surgical excision under local anesthesia. One‐year follow‐up revealed no sign of recurrences and malignant changes.     

Multiple keratotic papules on palm

Porokeratotic eccrine ostial and dermal duct nevus (PEODDN) is a rare nonhereditary malformation of the eccrine duct. A relationship with linear porokeratosis is not yet established; some consider it as a rare variant of porokeratosis involving the acrosyringium, whereas others consider it a separate entity based on distinctive clinical features and histologic accentuation within ostial structures. A 7-year-old girl presented with multiple asymptomatic keratotic papules over her right palm, present since the age of 6 months. These papules were arranged in a linear distribution over the palm and middle finger of the right hand. Most of the papules were discrete. However, lesions on the middle finger coalesced to form a plaque. Histology revealed a keratin filled deep invagination of the epidermis, notable for a column of parakeratosis ("cornoid lamella"). The dermis was notable for dilated eccrine ducts and absent inflammation. Considering the clinical and histological evidence, a diagnosis of PEODDN was made. Its clinical resemblance to linear lichen planus and linear porokeratosis is discussed. Also, we provide a brief review of this rare condition.     

Co-existence of variants of porokeratosis: a case report and a review of the literature

Rarely, different variants of porokeratosis may coexist in an individual patient or their family members. A patient with the linear form of porokeratosis present since birth subsequently developed the disseminated superficial actinic form at a later age. A review of the literature pertaining to the coexistence of variants of porokeratosis suggests a significant association between the linear and disseminated superficial actinic forms. Genetic linkage between different variants and the basis for their association is discussed.     

A case of extensive linear porokeratosis with evaluation of topical tretinoin versus 5-flourouracil as treatment modalities

A 19-year-old male presented with linear raised lesions over extensive areas of his body that followed Blaschko's lines. The lesions were asymptomatic with ridged borders. Histopathology confirmed a diagnosis of porokeratosis. He was given topical tretinoin and topical flourouracil for local application on specified areas. The cosmetic acceptability and the safety profile of tretinoin were found to be better than those of flourouracil. However, both the agents were equally efficacious. A rare case of extensive porokeratosis with comparative evaluation of two treatment modalities is hereby presented.     

Linear porokeratosis with bone abnormalities treated with compounded topical 2% cholesterol/2% lovastatin ointment

We describe a case of linear porokeratosis with associated bone resorption in a 17‐year‐old female with marked improvement after 2% cholesterol/2% lovastatin ointment application. Porokeratosis is a heterogenous group of keratinization disorders characterized by a cornoid lamella, consisting of focal dyskeratotic cells in the granular layer and columns of parakeratosis. The pathogenesis of porokeratosis is not fully elucidated; however, germline mutations have recently been identified in the mevalonate pathway which can lead to a buildup of metabolites that could play a role in dysmaturation. There has only been one prior report of an affected distal digit with underlying bone resorption in association with linear porokeratosis.     

Generalized linear porokeratosis: a rare entity with excellent response to acitretin

Linear porokeratosis is a rare disorder of keratinization that usually presents at birth. We report a 17-year-old male with generalized linear porokeratosis, a very rare variant of porokeratosis, with extensive involvement of the trunk and extremities along with nail and genital involvement. The patient was treated with oral acitretin with excellent clinical response.     

Verrucous porokeratosis of Mibelli on the buttocks mimicking psoriasis

The typical presentation of porokeratosis of Mibelli is of a solitary plaque with a prominent raised border cleaved by a central furrow. The central portion of the plaque is usually slightly atrophic. The plaques vary in size from a few millimeters to several centimeters in diameter and tend to be acrally distributed, though they can occur on any part of the body. We report an unusual case of verrucous porokeratosis of Mibelli, localized to the natal cleft, that mimicked psoriasis. This entity, though unusual, is not unique. Two similar cases of verrucous porokeratosis of Mibelli limited to the natal cleft region and resembling psoriasis have been reported in the British literature. Verrucous porokeratosis of Mibelli localized to the natal cleft appears to be a distinct clinical entity that can mimic psoriasis. Better recognition of this form of porokeratosis of Mibelli may result in earlier diagnosis and initiation of appropriate therapy.     

Type 2 segmental manifestation of disseminated superficial porokeratosis showing a systematized pattern of involvement and pronounced cancer proneness

Nine tumors of squamous cell carcinoma developed in a 61-year-old Japanese woman with linear porokeratosis. She had disseminated superficial porokeratosis, but a linear arrangement of pronounced lesions was found only on the left side of the body, and all of the tumors arose on the linear lesions on the left side of the body. Some of her family members had disseminated superficial porokeratosis. This case may represent a type 2 segmental manifestation of disseminated superficial porokeratosis showing a systematized pattern of involvement and pronounced cancer proneness.     

Multiple squamous cell carcinomas complicating linear porokeratosis

Linear porokeratosis is a distinctive variant of porokeratosis with malignant transformation, a known but infrequently reported complication. We report a case of linear porokeratosis on the right leg of a 57-year-old man present since infancy that, over a 2-year period, developed two squamous cell carcinomas within the lesion. Concurrent right inguinal lymphadenopathy was demonstrated on biopsy to be reactive in nature.     

Porokeratosis plantaris, palmaris, et disseminata

A 58-year-old man and his son presented with the clinical and histologic characteristics of porokeratosis plantaris, palmaris, et disseminata. Porokeratosis plantaris, palmaris, et disseminata also occurred in two other family members. Marked improvement was demonstrated with oral aromatic retinoid (Tigason) therapy. The differential diagnosis from the other types of porokeratosis is discussed. It is suggested that punctate porokeratosis is a form fruste of porokeratosis plantaris, palmaris, et disseminata.     

Linear porokeratosis of Mibelli and DSAP

Linear porokeratosis and disseminated superficial actinic porokeratosis (DSAP) are clinical variants of porokeratosis. We report the rare coexistence of these two variants. Porokeratosis is a genodermatosis which has at least five different clinical variants; Mibelli, linear, DSAP, plantaris palmaris et disseminata, and punctate (Wade & Ackerman, 1980). All of these manifest the distinctive peripheral keratotic ridge which histologically corresponds to the cornuid lamella. Although lesions of porokeratosis of Mibelli and linear porokeratosis are sometimes seen together in individuals, the coexistence of other porokeratotic variants is rare.     

Punctate Porokeratosis. A Clinical Variant of Porokeratosis of Mibelli

Punctate porokeratosis is not usually recognized as a clinical form of porokeratosis of Mibelli. Two cases of punctate porokeratosis are presented. Other punctate lesions with similar clinical features which should be considered in the differential diagnosis are discussed.     

Porokeratosis in Singapore: an Asian perspective

Porokeratosis is a rare disorder of skin keratinisation characterised by a cornoid lamella. We reviewed its associations with immunosuppression and phototherapy, as well as the risks of malignant progression. This is a retrospective review on all cases of porokeratosis seen at the National Skin Centre, Singapore, between 2000 and 2010. A total of 94 patients were reviewed. Clinical and histological diagnoses were confirmed in 63% patients. Most patients were Chinese (89%) with a mean age of 51.6 years. The male to female ratio was 1.4:1. The four main clinical variants were classical porokeratosis of Mibelli (56%), disseminated superficial actinic porokeratosis (DSAP) (18%), disseminated superficial porokeratosis (DSP) (11%), and linear porokeratosis (13%). Phototherapy-induced porokeratosis, seen in three patients, is rare. Seven cases of porokeratosis occurred in patients who were immunosuppressed. Progression of porokeratosis to malignancy is uncommon and was observed in three patients. The most common treatments included cryotherapy (26.5%) as well as topical steroids or retinoids (38.1%). A good response, defined as clear or almost clear lesions, occurred in 16% patients. The most common presentation of porokeratosis in our review was a middle-aged male patient with an asymptomatic lesion of porokeratosis of Mibelli over the extremities. No particular immunosuppressive drug was implicated. Porokeratosis associated with ultraviolet phototherapy or malignancy is rare. Progression of porokeratosis to malignancy arose in the disseminated variants, with a possible correlation with age. This is the largest institutional retrospective review of porokeratosis to date and highlights the major epidemiological characteristics of this condition.