Clinical Characteristics and Inciting Agents for Pseudoporphyria: The Mayo Clinic Experience, 1996–2020

ABSTRACT GENERAL PURPOSE To raise awareness regarding the clinical presentations of patients with pseudoporphyria. TARGET AUDIENCE This continuing education activity is intended for physicians, physician assistants, nurse practitioners, and registered nurses with an interest in skin and wound care. LEARNING OBJECTIVES/OUTCOMES After participating in this educational activity, the participant will: 1. Describe the clinical presentation of pseudoporphyria. 2. Identify the differential diagnoses of blistering lesions on hands and feet. 3. Outline the management options for patients with porphyria. BACKGROUND Pseudoporphyria is an uncommon immunobullous disease that is clinically and histopathologically similar to porphyria cutanea tarda but without abnormal porphyrin levels. Limited case reports and case series of pseudoporphyria have been published. OBJECTIVE To describe the clinical characteristics and inciting agents for patients with pseudoporphyria. METHODS Health records were retrospectively reviewed for patients treated at an integrated multiregional health system from 1996 through 2020. To report results, the authors used descriptive statistics, median (range) for continuous variables, and number (percentage) for categorical data. RESULTS In total, 23 patients met the inclusion criteria: 13 men and 10 women. The most common medications causing pseudoporphyria were nonsteroidal anti-inflammatory drugs, the antihypertensive agent hydrochlorothiazide, and retinoids. All patients had blisters and reported photosensitivity. Seven patients (30.4%) also had scarring, and one (4.3%) had milia. All patients had normal porphyrin levels in their serum, urine, and stool. Among patients with remission, symptoms resolved at a median of 2.5 months (range, 1 week to 24 months) after discontinuation of the suspected inciting medication. Four patients, however, had persistent symptoms at a median of 6 months (range, 2–9 months). CONCLUSION Because pseudoporphyria is a diagnosis of exclusion, clinicians should familiarize themselves with the presentation and management of this uncommon condition.