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.

Keywords
Scar tumour; positron emission tomography-computerized tomography; ¹¹C-acetate; F-18 Fluorodeoxyglucose