Disseminated superficial porokeratosis

Introduction

Porokeratosis is a specific disorder of keratinization. Clinically the basic lesion is a sharply demarcated and hyperkeratotic plaque with central atrophy. Histopathologically it is characterised by the presence of cornoid lamella.[1]

The lesions of classical porokeratosis were described by Mibelli in 1893. In 1966 disseminated superficial actinic porokeratosis (DSAP) was described by Cherosky. Five clinical variants are recognized (1) Porokeratosis of Mibelli, (2) Disseminated superficial porokeratosis, (3) Disseminated superficial actinic porokeratosis, (4) Porokeratosis palmaris et plantaris disseminate, (5) Punctate porokeratosis.

Disseminated superficial porokeratosis (DSP) usually starts in 3rd and 4th decades and it slowly progresses over years. Genetic studies show that DSP is inherited as autosomal dominant mode. Females are more affected than males.

Early lesions of disseminated superficial porokeratosis (DSP) are small keratotic papules with central dell. They may berythematous or pigmented. They enlarge to form superficial ring like lesions with slight central atrophy surrounded by discrete ridge topped by furrow. It mainly involves extremities in a bilateral symmetric fashion. Lesions spare the axillary vaults, inguinal folds, perigenital region, palms, soles and mucous membranes.[1] [Figure - 1]

Case Report

A 65-year-old male diabetic presented to us with itchy, hyperpigmented and erythematous plaques involving the trunk and extremities of 10 years duration. He gave h/o taking glibenclamide for the last 8 years and his diabetic state was under control. He gave h/o developing small itchy papules on the right flank which gradually increased in size to form well defined scaly hyperpigmented plaque. Similar lesions developed over the back, front of chest, both upper and lower limbs. [Figure - 2]

Cutaneous examination revealed multiple erythematous and hyperpigmented well defined scaly plaques of variable sizes ranging from 2 cms to 8 cms. The plaques were distributed on the extensor aspect of both upper and lower limbs. A well defined hyperpigmented plaque of 8x4 cms size was seen over the right lower back. A plaque on the left forearm showed rim with furrow. Palms, soles, hair and nails were normal. Oral and genital mucosae were normal. With these clinical findings a provisional diagnosis of disseminated superficial porokeratosis was made. Bowens disease, superficial spreading basal cell carcinoma were also considered in the differential diagnoses. Routine laboratory investigations and X-ray chest were normal. Blood for HIV was negative. Histopathology of skin biopsy which confirmed the diagnosis showed hyperkeratosis, patchy parakeratosis, cornoid lamella, absence of granular layer below the cornoid lamella and nonspecific dermal inflammatory infiltrate.

Discussion

There have been reports of association of disseminated superficial porokeratosis with systemic diseases like diabetes and liver disease. The reported case of disseminated superficial porokeratosis is also a known diabetic. However the association of disseminated superficial porokeratosis with diabetes could not be explained. Jang et al have reported similar association of DSP with diabetes.[2]

Our patient no liver disease either clinically or biochemically. Park et al have reported a case of disseminated superficial porokertosis associated with chronic liver disease ( Cirrhosis).[3] A review of the literature revealed that three cases developed porokeratosis when their liver functions declined and that in one case the porokeratosis disappeared spontaneously with liver transplantation. The case is reported for its rarity and its rare association with diabetes.