Pulmonary tuberculosis presenting with cluster sign and galaxy sign

In a routine medical check-up, a healthy man in his 20s was found to have an upper left lung abnormality. Subsequent chest CT revealed the cluster sign (CS) and galaxy sign (GS). Although tests such as sputum analysis and interferon-gamma assays reduced the likelihood of tuberculosis, these abnormalities remained unchanged. A lung biopsy indicated non-caseating granuloma unrelated to tuberculosis. Initially suspected of sarcoidosis, the patient later developed fever and malaise. Follow-up CT showed CS progressing to a cavitatory shadow and GS intensification. The detection of Mycobacterium tuberculosis (M. tuberculosis) in a subsequent sputum analysis prompted treatment with antitubercular drugs, leading to symptom relief. CS and GS are usually associated with sarcoidosis but can also occur in tuberculosis, connected to slower pathogen growth and lower isolation rates. Furthermore, pulmonary tuberculosis may ultimately be present even when biopsies show non-caseating granulomas that are not typical of M. tuberculosis and sputum culture results are negative for M. tuberculosis. Tuberculosis should not be ruled out lightly, and patients should be carefully followed-up.