Pseudoporphyria—a diagnostic challenge: A case series and a proposed diagnostic algorithm

Abstract

Differential diagnosis of dermatoses presenting with skin fragilityand blisters in photo-exposed areas is broad and includes porphyrias, autoimmune bullous diseases (ABD), and phototoxicities such as pseudoporphyria. 1 Pseudoporphyria is a bullous photodermatosis with a clinical presentation and histology similar to that of porphyria cutanea tarda (PCT), although with no porphyrin increase. 1,2 Pseudoporphyria is infrequent (<150 reported cases), probably underdiagnosed/underreported, and can represent a diagnostic challenge. 1,2 Here, we present a series of cases with pseudoporphyria and propose a diagnostic algorithm.

The phenomenon of phototoxicity and long-term risks of commonly prescribed and structurally diverse drugs

“…Shortly after coming to market in the 1950s, the use of thiazide diuretics were associated with incidences of phototoxicity [ 49 ]. In addition to typical phototoxic clinical presentations, rare manifestations include eczematous lesions, lichenoid eruptions, pseudoporphyria, and photoleukomelanoderma [ 133 , 134 , 202 ]. Oddly, eczematous lesions are reported to continue after discontinuation of the thiazide drug [ 49 ].…”

“…Differentiating phototoxic eruptions from other skin eruptions is essential to avoid unnecessary changes to therapy, particularly for those on medications treating serious medical conditions, as in the case of patients with melanoma treated with vemurafenib [ 219 ]. In patients who develop pseudoporphyria-type reactions, elevated protoporphyrin levels may need to be checked to rule out porphyria [ 24 , 202 ]. If phototoxicity due to vemurafenib treatment is severe and warrants removal of the drug, dabrafenib may be an alternative treatment with a decreased risk of phototoxicity [ 220 ].…”