Eosinophilia and the Elusive Skin Condition, Spongiotic Dermatitis

Chronic eosinophilia with cutaneous involvement presents a diagnostic challenge, as the differential diagnosis is very broad, including eosinophilic dermatoses, hypersensitivity reactions, autoimmune diseases, and infections. Spongiotic dermatitis (SD) is a histopathological pattern commonly observed in inflammatory skin conditions. It is a non-specific finding that requires clinical correlation. This case describes a 68-year-old female with a five-year history of chronic eosinophilia who presented with acute right leg pain, swelling, and a diffuse pruritic rash covering >90% of her body surface area. She reported recurrent flares of erythematous plaques with bilateral eye swelling and had a history of recent international travel. Laboratory testing revealed marked eosinophilia, elevated IgE levels, and increased inflammatory markers, while a punch biopsy demonstrated SD with eosinophilic infiltration. Given the histopathologic findings and systemic involvement, multiple etiologies were considered. This report highlights the diagnostic complexity of SD in the context of chronic eosinophilia, emphasizing the importance of distinguishing between mimicking conditions through a thorough clinical and histopathologic evaluation.