Tuberculous scar tumour detected by dual tracer positron emission-computerised tomography in a tuberculous endemic area

Tuberculous scar tumour is difficult to diagnose as it does not present with any respiratory symptoms and has a negative chest X-ray. This is a case report on the use of dual tracer 11C-acetate and 18F-fluorodeoxyglucose (18FDG) whole body positron emission tomography-computerised tomography (PET-CT) for detection of tuberculous scar tumour. A 44-year-old Chinese female was incidentally found to have a raised serum Ca 19.9. Magnetic resonance imaging of the whole abdomen, upper endoscopy, and colonoscopy were all unremarkable. A low-dose computed tomography (CT) of the thorax showed bilateral upper lobe fibrosis. Bronchoalveolar lavage for culture and cytology was negative. A dual tracer 11C-acetate and 18FDG whole body PET-CT showed that the left upper lobe fibrosis was hypermetabolic in nature. It was more avid for 11C-acetate than for 18FDG. The left upper lobe lesion was subsequently confirmed on open lung biopsy to be a moderately differentiated adenocarcinoma. Therefore, in a tuberculous endemic region, dual tracer whole body PET-CT with 11C-acetate and 18FDG may have a role in the early detection of tuberculous scar tumour in the lung.