Peeled off water chestnut in the knee

Abstract Fibroma of tendon sheaths (FTS) is an uncommon soft tissue tumour which arises from the synovial sheath of tendons. We report a histologically proven case with intrarticular ‘fibroma of tendon sheath’ originating from the joint capsule of the knee, an even rarer entity, in a middle-aged female presenting with knee pain, swelling with limited range of motion. MRI and arthroscopy studies revealed an intra-articular mass originating from the synovial membrane with lobulated contours. Open excision was performed because of the large size of the mass, making it inaccessible arthroscopically. The patient is symptom free since the surgery done 15 months back.