Reversed halo sign in active pulmonary tuberculosis.

To cite: Nattusamy L, Madan K, Bhalla AS, et al. BMJ Case Rep Published online: [please include Day Month Year] doi:10.1136/ bcr-2013-202981 DESCRIPTION A 35-year-old male patient presented with history of fever and cough of 2 months duration. The patient had lost appetite and 8 kg weight over 2 months. On examination of the respiratory system, scattered crackles were audible bilaterally. Rest of the systemic examination was normal. Chest radiograph demonstrated bilateral ill-defined alveolar opacities and left side apical pleural thickening with volume loss (figure 1). CT of the thorax demonstrated multiple complete or incomplete (crescent shaped) nodular areas of consolidation surrounding a region of ground-glass opacity (reversed halo sign) (figure 2). Also seen was left lung volume loss along with compensatory right lung hyperinflation. Sputum examination was positive for acid-fast bacilli (3+) and Sputum GeneXpert MTB/RIF test was positive for Mycobacterium tuberculosis, sensitive to rifampicin. The patient was started on anti-tuberculosis (TB) therapy with four first-line drugs and improved. Reversed halo sign (also known as reverse halo sign, atoll sign or fairy ring sign) refers to the appearance of central lucency/ground-glass opacity which is surrounded by the air-space consolidation of crescentic or ring shape on CT of the thorax. Most frequently associated with cryptogenic organising pneumonia (COP), this sign has been reported in a number of conditions like invasive pulmonary fungal infections, pneumocystis pneumonia, TB, lymphomatoid granulomatosis, granulomatosis with polyangitis, sarcoidosis, pulmonary neoplasm’s and infarction, and following radiation therapy/radiofrequency ablation of lung malignancies. Presence of nodular walls and presence of nodules inside the halo is an important finding differentiating TB from COP, as was seen in our patient.