Disseminated Superficial Porokeratosis with Groove Sign

An 8-year-old girl presented to the dermatology outpatient department with multiple well-defined hyperkeratotic plaques with an elevated ridge-like border at numerous body sites for 2 years. On cutaneous examination, there were multiple well-defined skin-colored plaques with hyperkeratotic scales on the surface having a raised elevated thready border in the majority of the lesions. On close inspection, a groove was noticed at the periphery between the inner and outer margins of the plaques [Figure 1]. The lesions vary in size from 1 cm × 1 cm to the largest, measuring in size 10 cm × 3 cm distributed over the right upper limb, right axilla, right upper and lateral chest, lower back, and genitals. Her mucosal, hair, nail, palms, and soles examination were normal. Based on the above clinical findings, a diagnosis of disseminated superficial porokeratosis (DSP) was made, which was further supported by classical histopathology findings of coronoid lamella. This patient was started on oral acitretin (0.5 mg/kg), and her follow-up is awaited.Figure 1: Groove is noted between the inner and outer margin at the periphery of the plaque (shown with black arrow head)The characteristic lesion of porokeratosis presents as a hyperkeratotic plaque with a ridge-like border which corresponds to the histological finding of cornoid lamella.[1] Various clinical and morphological types are present, which include porokeratosis of Mibelli, DSP, disseminated superficial actinic porokeratosis (DSAP), linear porokeratosis, genito-gluteal porokeratosis, porokeratosis palmaris et plantaris disseminata and punctate porokeratosis.[2,3] DSAP is the most common variety.[2] Histopathology study shows the presence of tightly packed parakeratotic cells in a vertical column within an epidermal invagination giving rise to the cornoid lamella.[4] Dermoscopy shows a “white-track” structure at the periphery which corresponds to the cornoid lamella.[5] We are describing this case to demonstrate the groove sign in porokeratosis, which will help in the clinical diagnosis of the condition. Declaration of consent The authors certify that they have obtained all appropriate consent forms, duly signed by the parent(s)/guardian(s) of the patient. In the form, the parent(s)/guardian(s) has/have given his/her/their consent for the images and other clinical information of their child to be reported in the journal. The parents understand that the names and initials of their child/children will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.