Uncommon High Resolution Computed Tomography Features of Pulmonary Tuberculosis: A Case Series

Abstract

Classical imaging manifestations of pulmonary Tuberculosis (TB) include consolidation, cavitation, necrotic mediastinal lymphadenopathy and pleural effusions. On the other hand, atypical imaging findings of pulmonary TB are sometimes encountered which create a diagnostic dilemma; three such patients are reported here. The predominant finding in the first patient (24-year-old female) was diffuse cystic lung disease with associated bilateral secondary spontaneous pneumothoraces. The subacute onset of symptoms, associated nodules and ground glass opacities were a pointer towards an infective aetiology of the diffuse cysts in this case. The second patient (41-year-old female) presented with peribronchovascular and perifissural nodules with the galaxy or cluster sign leading to an erroneous diagnosis of sarcoidosis. However, the patient’s serum Angiotensin Converting Enzyme (ACE) levels were within normal limits; whereas her bronchial washings culture was positive for Mycobacterium TB. Therefore, this was actually a case of pulmonary TB with lymphatic involvement mimicking sarcoidosis. In the third patient (20-year-old female), there were pulmonary parenchymal lesions with the reversed halo sign classically described in cryptogenic organising pneumonia. Micronodularity in the wall and central part of the reversed halo lesion clinched the diagnosis of TB in this case. Laboratory investigations revealed acid fast bacilli or caseating granulomas consistent with TB in all these patients. Therefore, awareness regarding the atypical Computed tomography (CT) findings and a high index of suspicion is necessary to avoid delays in diagnosis and enable early institution of appropriate Antitubercular Therapy (ATT) in such cases.