‘Coin Lesion’ in Chest Radiograph Presenting as Round Pneumonia with Eccentric Cavitation in HRCT Thorax: Tuberculosis or Malignancy-A Real Puzzle!

Abstract

Lung malignancies have diverse radiological presentations such as coin lesions, mass lesion, hilar abnormalities, lung collapse and mass with pleural effusion. ‘Coin lesion’ radiologically defined as solitary, well demarcated, coin shaped lung parenchymal opacity with surrounding normal lung parenchyma. Coin lesions having propensity of calcification and cavitation. Calcification usually indicates benign nature while cavitation will indicate benign, infective and malignant lung pathology. Eccentric cavitation favours lung malignancy and central cavitation usually seen in infective pathology over malignancy. Round pneumonia is commonly described in paediatric cases and adults with comorbidities. Round pneumonia is defined as a round shaped consolidation secondary infective process. Tuberculosis causing round pneumonia and coin shaped opacities or coin lesions are not very commonly described in literature. In this case report, a 42-year male, uncontrolled diabetes mellitus presented with constitutional symptoms for one month duration with partial response to medical treatment. Chest x-ray showed coin lesion or coin shaped opacity in the left lower zone in the paracardiac area. HRCT thorax showed coin lesion with central breakdown or central lucency and round pneumonia. Contrast CT thorax showed eccentric cavitation with enhancement favouring malignancy. We have done bronchoscopy and BAL evaluation confirmed pulmonary tuberculosis. BAL cytology documented acid-fast bacilli in smear and MTB genome with rifampicin sensitivity in cartridge based nucleic acid amplification test. Treatment initiated with anti-tuberculosis (ATT) & short acting insulin according to blood sugar level. We have recorded near complete radiological resolution, bacteriological cure after six months with good compliance. High index of suspicion is must in cases with ‘coin lesion’ in chest radiograph with underlying comorbidity as diabetes mellitus with constitutional symptoms. HRCT thorax will help in defining characteristics of coin lesions such as cavitation and calcification. Bronchoscopy is a very crucial technique in evaluating these cases and conforming infective or malignant pathology for coin lesions.