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

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.

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. To describe the clinical characteristics and inciting agents for patients with pseudoporphyria. 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. 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, 2­9 months). Because pseudoporphyria is a diagnosis of exclusion, clinicians should familiarize themselves with the presentation and management of this uncommon condition.

Monoclonal gammopathy in the setting of Pyoderma gangrenosum.

Pyoderma gangrenosum (PG) is a neutrophilic dermatosis characterized by ulcerative painful lesions with violaceous undermined borders. Up to 75% of PG cases develop in association with an underlying systemic disease. Monoclonal gammopathy is reportedly a concomitant condition with PG, with studies indicating immunoglobulin (Ig) A gammopathy as the most common. Whether gammopathy is associated with PG or is an incidental finding has been debated. We sought to investigate the association and characteristics of gammopathy in patients with PG. We retrospectively identified PG patients at our institution from 2010 to 2022 who were screened for plasma cell dyscrasia. Of 106 patients identified, 29 (27%) had a gammopathy; subtypes included IgA (41%), IgG (28%), and biclonal (IgA and IgG) (14%). Mean age was similar between those with and without gammopathy (60.7 vs. 55.9 years; P = .26). In addition, hematologic or solid organ cancer developed in significantly more patients with vs. without gammopathy (8/29 [28%] vs. 5/77 [6%]; P = .003). Among the subtypes of gammopathy, IgG monoclonal gammopathy had the highest proportion of patients with subsequent cancer development (4 of 8 patients, 50%). Study limitations include a retrospective, single-institution design with a limited number of patients. Overall, our data show a high prevalence of gammopathy in patients with PG; those patients additionally had an increased incidence of cancer, especially hematologic cancer.