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Radiographic appearances of pulmonary tuberculosis :. There are no definitive radiographic appearances of tuberculosis. Classically, tuberculosis affects the apices and upper zones more frequently than other areas of the lung fields. Lesions may appear as small nodules or patchy infiltration which may be unilateral or bilateral. The best radiographic view to see the apices clearly, without bony structures in the way, is the apical lordotic view. If the disease heals, calcified lesions may appear in the lung and ipsilateral hilar nodes. If the disease progresses a larger area of pneumonia will develop and there may eventually be cavity formation. Cavities in the upper zones are common in tuberculosis. Their appearance is a classical sign. However, it is important to remember that there are other cavitating pneumonias, for example staphylococcus, klebsiella and some anaerobic streptococci. Once cavitation has occurred in tuberculosis, there is a high risk of bronchopneumonic spread to other parts of the lung where bacilli are inhaled to other lung segments. When this occurs, tuberculous bronchopneumonia develops and the radiographic appearances are those of extensive unilateral or bilateral soft opacities. These findings are indistinguishable from severe bacterial bronchopneumonia or aspiration pneumonia, except that cavities may be obvious in tuberculosis. Pleural effusions may develop and can be massive in tuberculosis: apical shadows of pulmonary tuberculosis may be present, usually in the ipsilateral lung. Tuberculomas may appear as dense, discrete, rounded nodules which may or may not calcify. The obvious differential diagnosis is lung cancer. Histological examination is advisable, either by bronchoscopy, per-cutaneous needle biopsy or thoracotomy. Remember that adenocarcinoma of lung may occur in non-smoking young patients, particularly females, in Hong Kong.
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