Unusual hematologic manifestation in Legionnaires’ disease: autoimmune hemolytic anemia

Abstract

Legionella pneumophila is an intracellular Gram-negative bacillus that causes legionellosis, classically recognized for its presentation as atypical pneumonia. Among its extrapulmonary manifestations, autoimmune hemolytic anemia (AIHA) is a rare complication, with few cases reported in the literature. We present the case of a 67-year-old man who presented with a progressive respiratory illness due to Legionella associated with severe hemolytic anemia. Epidemiological history, together with clinical features and laboratory findings, were key to establishing the diagnostic hypothesis. Timely treatment directed at both the etiologic agent and its complications led to a favorable outcome. Although AIHA is an uncommon manifestation of legionellosis, lack of awareness may lead to underdiagnosis, diagnostic uncertainty, and management errors. Finally, a pathophysiological explanation is proposed based on previous reports and available evidence.