Pulmonary puzzle

A 58-year-old man who never smoked and was under follow-up for polymyositis associated with fibrotic interstitial lung disease was found to have an incidental opacity in the right upper lobe on a chest radiograph. He had been treated with daily azathioprine 200 mg and prednisolone 10 mg for 15 years. A CT chest revealed a mass-like lesion of relatively low attenuation suggesting necrosis (figure 1). Bronchoalveolar lavage was negative for microbiology and cytology. CT-guided biopsies were reported as showing necrosis and inflammation only. A month later, he developed cough with malodorous sputum, generalised fatigue, mild fevers, sweats and dyspnoea.