A rare case of giant cell tumour arising from anterior cruciate ligament: Its diagnosis and management.

Tenosynovial giant cell tumour is a locally aggressive tumour arising from the synovia of the fibrous tissue surrounding the joints, tendon sheaths and tendons. Areas of predilection are the hand, and in the case of synovial joints, the knee joint is particularly affected. We describe a rare case of an intra-articular localized tenosynovial giant cell tumour arising from the anterior cruciate ligament (ACL) in a 27 year male who presented with pain and giving way of his left knee without prior history of any trauma. Tests for internal derangement of knee were negative. MRI reported an ACL tear with a heterogeneous fibrous mass attached to the distal part, most probably an organized haematoma. It was decided to do a diagnostic arthroscopy before proceeding for ACL reconstruction. Arthroscopy revealed a purple coloured mass attached to distal part of ACL. The mass was removed piecemeal using an additional posterolateral portal. ACL was found intact. Histopathology reported it to be tenosynovial giant cell tumour. The patient was asymptomatic at each subsequent follow up. It is a rare diagnosis which presented as an ACL tear; in such suspected cases it is prudent to perform a diagnostic arthroscopy before going for ACL reconstruction.