The resemblance between pustular psoriasis (PP) and acute generalized exanthematous pustulosis (AGEP) challenges their diagnosis and treatment. They possess significant clinical and histopathologic overlap. PP is an inflammatory disorder with numerous clinical subtypes, but all with sterile pustules composed of neutrophils. AGEP is a severe cutaneous adverse reaction characterized by nonfollicular sterile pustules. 

Clinical features that pints towards PP over AGEP include a history of psoriasis and the presence of scaling plaques. While histologically, eosinophilic spongiosis, vacuolar interface dermatitis and dermal eosinophilia favor a diagnosis of AGEP over PP. 

To note, PP and AGEP have different clinical courses and treatments. Treatment of PP includes topical steroids, oral retinoids and systemic immunosuppressants. The newer therapies targeting interleukin (IL)-36, IL-23, IL-1 and phosphodiesterase-4 are also under investigation. However, removing the offending agent remains a cornerstone in treating AGEP.

Source: Sussman M, Napodano A, Huang S, et al. Pustular psoriasis and acute generalized exanthematous pustulosis. Medicina (Kaunas). 2021;57(10):1004.