Presentation
Admitted due to left knee pain swelling and pus discharge from arthroscopy skin incision.
Patient Data
Initial Frontal and Lateral X-rays show soft tissue swelling with minimal bony destruction at the level of the knee joint.
Large lobulated homogenously and vividly enhancing high T2 and low T1 lesion (measuring about 7.8 x 9.0 x 6.2 cm) arising from the thickened left knee synovium extending superiorly, wrapping around the anterior part of the distal femur bone and inferiorly around the proximal tibia. This stretches the joint ligaments and encases the neurovascular bundle. There is bone invasion and cortical breach at the level of the knee joint with enhancement suggestive of osteomyelitis.
Surrounded by multifocal loculated peripherally enhancing collections, one opening anterolaterally into the skin by sinus. The largest pocket measures 5.7 x 2.8 cm.
Case Discussion
This patient lives in a TB endemic region had recurrent visits to the ER over the last 6 months complaining of mild knee pain.
Excisional biopsy with bone, skin and soft tissue specimens were negative for malignancy and showed caseating granulomatous inflammation highly suggestive of TB.