Assessment of early response to treatment in extrapulmonary tuberculosis: Role of FDG-PET.

Sir,

We report an elderly man on dialysis who was evaluated for a suspected bronchogenic carcinoma with fluorodeoxyglucose positron emission tomography (FDG-PET) computed tomography (CT) scan. His scan revealed multiple mediastinal lymph nodes and skeletal lesions [Figure 1] which were later confirmed to be tuberculosis (TB) on TB PCR, Lowenstein–Jensen medium. Three days after initiation of anti-tubercular therapy (ATT), metabolic activity in lymph nodes decreased significantly [Figure 2] though the skeletal lesion activity persisted. Three months after ATT, there was complete resolution of both lymph nodal and skeletal lesions [Figure 3]. Earliest response to ATT on FDG-PET CT was reported to be at the end of eight-week therapy.[1] FDG-PET/CT is the imaging modality that is useful in detecting extra-pulmonary TB and also in assessment of early response to ATT as early as 3 days.

Figure 1

Fluorodeoxyglucose-positron emission tomography computed tomography scan showing multiple cervical and mediastinal group of lymhnodes along with skeletal lesions

Figure 2

Fluorodeoxyglucose-positron emission tomography computed tomography scan showing decreased tracer uptake in cervical and mediastinal lymphnodes, 3 days after initiation of anti-tubercular therapy

Figure 3

Fluorodeoxyglucose-positron emission tomography computed tomography scan showing normal uptake of tracer in the lymphnodes