A 41-year-old male was admitted to a hospital 10 months ago with a history of moderate fever, anorexia, difficulty in walking and throbbing pain in the right hip. MRI scan of the right hip joint showed joint effusion with erosions on the articular surface of the acetabular cavity and right iliopsoas abscess. Pus culture revealed acid-fast bacilli. Hip biopsy revealed necrotizing granulomatous inflammation with Langerhans giant cells suggestive of TB. Chest X-ray was unremarkable. He was subsequently started on antitubercular therapy, but was repeatedly found to have pus collections at the hip joint, which were aspirated. Thereafter, he developed a discharging sinus. A repeat MRI scan of the right hip joint revealed extension of the disease in the right acetabulum with involvement of head and neck of femur and a large right iliopsoas abscess extending into the adjacent musculature. Drainage of abscess with debridement and girdlestone arthroplasty was performed, with modification of antitubercular regimen. He responded poorly to the above treatment, owing to extreme drug resistance, and was subsequently referred for a PET/CT scan.
Whole body PET/CECT scan (skull base to mid thigh) was performed on an integrated PET/CT scanner (Discovery STE 16, GE Healthcare) 60 minutes after injection of 10 mCi of F-18 fluorodeoxyglucose (F-18 FDG) following a 6-hour fast. The study revealed an intensely FDG avid organized collection in the right hip joint space, with extension of the inflammatory process into the surrounding muscle and soft tissue [Figures 1 and 2]. A large, relatively photopenic abscess was noted in the right iliopsoas muscle [Figure 3]. Destructive changes in right acetabulum with post-arthroplasty changes were also seen. An FDG avid sinus track extending from the right hip joint was clearly visualized on the MIP image. Additionally, active mediastinal lymphadenopathy was also noted [Figure 1].