Case Report Giant Cell Tumour of Tendon Sheath Presenting as Ulnar Tunnel Syndrome: A Novel Technique of Tumour Dissection with Bipolar Cautry. Sanjay AgarwalaƬ, Abhijit KawalkarƬ, Sameer ChaudharyƬ Abstract: Giant cell tumour of the tendon sheath (GCTTS) is a slow growing rare benign tumour arising from the synovial cells of the tendon sheath. GCTTS occurs most commonly in the third to fifth decades of life in the flexor tendons of the hand, and only rarely involves other soft tissues or bone. Treatment of GCTTS is still controversial mainly because of the high recurrence rate of its frequent extensions in surrounding soft tissues and presence of satellite lesions. We present an interesting case of a GCTTS, over right wrist and forearm with a satellite lesion and presenting as ulnar tunnel syndrome in a 32 years male, and a novel technique of dissection with bipolar cautery to minimize the recurrence. Keywords: giant cell tumour of tendon sheath, bipolar cautery, ulnar tunnel syndrome Introduction A giant cell tumour of the tendon sheath (GCTTS) is a benign proliferative disorder of the synovium that may affect the tendon sheaths, joints, and bursae [1]. With an approximate incidence of 1/50,000 per population it remains an uncommon condition [2]. The incidence of GCTTS is higher in women than in men and mostly seen in the third to fifth decade. These lesions are characteristically slow- growing, nodular, painless, and usually asymptomatic. Conventional radiographs are usually normal or may show a soft tissue mass, and only rarely reveal some bone involvement[3]. However, secondary nerve compression, joint degeneration, and bone erosion can occur [3]. Local excision is the treatment of choice. But about 4 to 30 % of cases recur after surgical excision [4]. It has been suggested that recurrences develop most often in highly cellular tumours or lesions with a high mitotic count [4]. Here we are presenting the case of GCTTS with unique presentation and a specialised surgical technique used to minimise its recurrence. Case report A 32 years male patient presented to us with swelling over right wrist and distal forearm since 8 months. Initially the swelling was present over volar aspect of the wirst and distal forearm which was diagnosed as ganglion cyst over ulnar border. But gradually the swelling extended to dorsal aspect. (Fig-1A) At first the swelling was painless but patient started having pain over ulnar distribution of right hand 6months prior to presentation. He also developed tingling and numbness in right little and ring finger. There was no history of trauma or fever. On examination swelling was firm, lobulated, well circumscribed and not adhered to overlying skin but was adherent to underlying soft tissues. Local temperature was normal, there was no redness. The swelling was non pulsatile. Radiographs were non-conclusive showing only soft tissue shadow. Magnetic resonance imaging (MRI) of right wrist with forearm showed soft tissue mass contiguous with flexor digitorum superficialis, extending from volar to dorsal aspect, probably a ganglion cyst or giant cell tumour of tendon sheath. (Fig-1-B,C) Complete excision of tumour was planned and done under brachial block. V-shaped incision was taken over volar aspect of forearm and extended to dorsal side (Fig-2A) A brownish yellow multi lobulated tumour of around 4x3 cm was excised completely (Fig-2B), with meticulous dissection using bipolar cautery to minimize the chances of recurrence. (Fig-2C) A satellite lesion (Fig- 2D) was also excised along with the tumour, which was compressing the superficial branch of ulnar nerve at the Guyon's canal. Histopathology sections showed multi lobulated tumour with giant cells, foamy macrophages, hemosiderophages and stromal cell without atypia with hyaline stroma, which confirmed the diagnosis of tenosynovial giant cell tumour. (Fig-2E) Discussion Giant cell tumour of the tendon sheath (GCTTS) is a rare condition with an incidence reported at 0.5% [5]. It is the second most common soft tissue tumour of the hand and wrist, after synovial ganglion, occurring predominantly in females. Localisation to the hand and wrist is noted in about 70% of cases, with a propensity for the radial three digits, the volar aspect and the distal interphalangeal joint [5]. Our patient was 32 years male who presented with lesion over ulnar aspect of right forearm extending from volar to dorsal aspect. GCTTS has been known to impinge upon 1 Dept of Orthopaedics, P.D Hinduja National Hospital, Mumbai. India. Address for correspondence: Dr. Sameer Chaudhary Clinical associate, Dept of orthopaedics, Hinduja hospital, Mahim, Mumbai. Email- sameertch84@gmail.com Journal of Trauma & Orthopaedic Surgery 2016;11(1):37-39 Journal of Trauma & Orthopaedic Surgery | Jan-March 2016 | Volume 11 |Issue 1 | Page 37-39 Copyright © 2016 by The Maharashtra Orthopaedic Association | 37