Generalized Pustular Psoriasis Mimicking Acute Generalized Exanthematous Pustulosis: A Case Report

Abstract

Introduction: Generalized pustular psoriasis (GPP) is a rare but severe variant of psoriasis, characterized by widespread sterile pustules that may involve the entire body surface and are not limited to pre-existing psoriatic lesions. The diagnosis and management of GPP and acute generalized exanthematous pustulosis (AGEP) can be challenging due to the difficulty in distinguishing them both clinically and histopathologically. This case highlights the challenge of establishing a diagnosis of GPP and emphasizes the importance of re-evaluating differential diagnoses to provide the most appropriate therapy.

Case: A 52-year-old male presented with diffuse erythematous patches and pustular lesions over the entire body for two months, with exacerbation in the last five days. The pustules were associated with pruritus, burning, and pain. He had previously been diagnosed with AGEP and treated with methylprednisolone without improvement. Dermatological examination revealed generalized erythematous plaques with multiple papules and pustules, some confluent forming “lakes of pus,” accompanied by scaling and erosions. Histopathology showed hyperkeratosis, parakeratosis, hypogranulosis, Munro’s microabscesses, spongiform pustules of Kogoj, regular acanthosis, and dermal capillary dilatation with lymphocytic and neutrophilic infiltrates, consistent with GPP. The patient was treated with intravenous 31.25 mg every 12 hours, omeprazole 40 mg daily, diphenhydramine 1 ampoule/ 24 hours, and topical vaseline album mixed with desoximetasone 0.25% cream (1:1). After 7 days of the treatment, the lesion showed marked improvement but persisted partially.

Discussion: This case highlights the inherent difficulty in differentiating GPP form AGEP as both entities may present with extensive sterile pustules and overlapping histopathological features. The chronic course of the eruption, poor response to corticosteroid therapy, and the presence of characteristic histologic hallmarks such as Kogoj’s spongiform pustules and Munro’s microabscesses were key in establishing the diagnosis of GPP. These findings underscore the critical importance of thorough clinical evaluation supported by histopathologic assessment to achieve diagnostic accuracy.

Conclusions: A case of GPP in a 52-year-old man initially mimicking acute AGEP was reported. Clinical and histopathological evaluation confirmed the diagnosis, highlighting the essential role of skin biopsy due to overlapping features with AGEP.