Pulmonary tularemia: A diagnosis not to overlook

Tularemia is a zoonotic disease caused by Francisella tularensis, a highly virulent bacterium, with an increasing incidence worldwide. Pulmonary involvement is uncommon and often presents misleading clinical and radiological features. This case series aims to describe the clinical characteristics, imaging features, and management of patients with pulmonary tularemia. All cases diagnosed in our department between 2016 and 2023 were included. Seven patients were identified. Clinical presentation was nonspecific, most frequently including fever, respiratory symptoms, fatigue, and headaches. Chest computed tomography (CT) consistently revealed mediastinal lymphadenopathy and pulmonary nodules, sometimes associated with subpleural micronodules or pleural effusion. In three patients, positron emission tomography/CT demonstrated intensely hypermetabolic lesions, highly suggestive of malignancy. CTguided biopsies performed in two patients revealed a non-specific necrotizing granulomatous inflammation. Tularemia serology was positive in all patients. Treatment consisted of doxycycline in six patients and ciprofloxacin in one patient, with a mean duration of 16.7 days. Clinical outcome was favorable in all cases. This series highlights the challenging diagnosis of pulmonary tularemia due to its nonspecific clinical and radiologic features, which may mimic lung cancer or lymphoma, often resulting in delayed diagnosis and unnecessary invasive investigations. Early serologic testing should be considered in endemic areas or in patients with a relevant history of exposure, to ensure prompt and appropriate treatment.