Penile porokeratosis of Mibelli with eosinophilic spongiosis: A case report

Abstract

Introduction Porokeratosis is a form of abnormal keratinization with porokeratosis of Mibelli (a localized variant) as the second most common form1. Eosinophilic spongiosis is presence of eosinophils with the epidermis in areas of spongiosis2. Porokeratosis with eosinophilic spongiosis has only rarely been reported. We report a patient with penile porokeratosis of Mibelli with the unusual finding of eosinophilic spongiosis. Case Report A 55-year-old male presented for skin cancer screening. An 8mm nontender red plaque with overlying scale was noted on the dorsal penile shaft. The patient had no history of similar lesions. Treatment with hydrocortisone 2.5% twice a day for 14 days was initiated, but the lesion did not improve. At follow-up, a punch biopsy was performed revealing typical histopathologic features of porokeratosis with a cornoid lamella. An unusual finding was the presence of eosinophils within the epidermis adjacent to the cornoid lamella. The patient did not follow up when offered treatment. Discussion Porokeratosis with eosinophilic spongiosis is a rare histopathological feature that has only been described in three case reports to our knowledge. All three previously reported cases occurred in patients with disseminated superficial actinic porokeratosis3,4,5. In contrast to previous reports, our patient presented with a single lesion. Recognition of this phenomenon may be helpful because eosinophilic spongiosis usually suggests a specific inflammatory differential diagnosis, and porokeratosis may not be considered. Porokeratosis, including the localized variant, may be added to the potential causes of eosinophilic spongiosis.