The CT target sign as a criterion for the differential diagnosis between tuberculosis and organizing pneumonia

A 61-year-old male patient developed fever, dry cough, myalgia, headache, and arthralgia and was treated with prednisone and symptom-based medications.The decision to initiate corticosteroid therapy instead of antibiotics was based on the atypical clinical and laboratory features of a bacterial infection, which led us to consider it an inflammatory or autoimmune disease.Five days later, the patient's condition worsened and was hospitalized.The patient denied any other signs or symptoms.Complementary examinations including a respiratory viral panel yielded no significant findings.Chest radiography revealed inhomogeneous opacities in the left lower lobe of the lung (Figure 1A).Chest CT findings were compatible with the