Case Report A rare case of giant cell tumour arising from anterior cruciate ligament: Its diagnosis and management Sanjay Agarwala MCh Orth, Pranshu Agrawal M.S Orth * , Pradeep Moonot FRCS Tr & Orth, Anshul Sobti D.N.B Orth P.D. Hinduja National Hospital & Medical Research Centre, Veer Savarkar Marg, Mahim, Mumbai 400016, India article info Article history: Received 5 September 2014 Accepted 13 December 2014 Available online 13 January 2015 Keywords: Tenosynovial Giant cell tumour Intrarticular ACL abstract 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 predilec- tion 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. His- topathology reported it to be tenosynovial giant cell tumour. The patient was asymptom- atic 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. Copyright © 2014, Delhi Orthopaedic Association. All rights reserved. 1. Introduction Tenosynovial giant cell tumour is a locally aggressive tumour arising from the synovia of the fibrous tissue surrounding the joints, tendon sheaths, mucosal bursas, and tendons. 1,2 The various synonyms used to describe the tumour are: giant cell tumour of tendon sheath, nodular tenosynovitis, pigmented villonodular synovitis, fibroxanthoma and fibrous histiocy- toma. 3 The four clinicopathologic variants of tenosynovial giant cell tumour are localized, diffuse extra-articular, diffuse intra-articular (diffuse pigmented villonodular synovitis), and malignant. 4,5 The localized type of tenosynovial giant cell tumour is defined as a circumscribed lesion that is micro- scopically not infiltrating into the fat or skeletal muscle. Areas of predilection are the hand, and in the case of synovial joints, * Corresponding author. Tel.: þ91 7567734509; fax: þ91 22 24440425. E-mail address: pranshuorthodoc@gmail.com (P. Agrawal). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/jcot journal of clinical orthopaedics and trauma 6 (2015) 140 e143 http://dx.doi.org/10.1016/j.jcot.2014.12.005 0976-5662/Copyright © 2014, Delhi Orthopaedic Association. All rights reserved.