Abstract

Introduction
The term autoinflammatory keratinization diseases (AIKDs) was recently proposed as a unifying concept for diseases characterized by inflammation in the epidermis and upper dermis leading to hyperkeratosis, caused by genetic perturbations of the innate immune system. We present a case of a patient with hidradenitis suppurativa (HS) and porokeratosis, two AIKDs.

Case
A 52-year-old man presented to the dermatology clinic for a 10-year history of painful draining nodules affecting the axilla and genitalia consistent with HS, and a 2-year history of a hyperkeratotic rash concerning for porokeratosis palmaris et plantaris disseminata. He was started on adalimumab for HS, but experienced enlargement of hyperkeratotic verrucous plaques. Biopsies demonstrated hypertrophic porokeratoses involving cystic hair follicles. Collectively his symptoms were deemed to be consistent with porokeratosis and HS in the context of the autoinflammatory keratinization disease spectrum. Additional biopsy of an abdominal lesion demonstrated SCC arising within porokeratosis, which was treated with Mohs surgery. The patient was treated with acitretin, dapsone, and infliximab with improvement in HS and porokeratosis symptoms.

Discussion
The concurrence of porokeratosis and HS has been rarely reported in the literature; interestingly, all cases, including ours, describe patients with follicularly associated porokeratoses in conjunction with HS. Recent studies found that mevalonate kinase pathway mutations underlie many cases of porokeratosis. Two recent cases of concurrent mevalonate kinase deficiency and HS were reported, raising the question of whether mevalonate pathway mutations could have a role in HS. Further study is needed to determine whether overlapping mutations could predispose to both AIKDs.