A giant cell tumours of the tendon sheath (GCTTS) is an uncommon usually benign lesion that arises from the tendon sheath. It is unclear whether these lesions represent neoplasms or simply reactive masses. The are also known as pigmented villonodular tumour of the tendon sheath (PVNTS).
Clinically these masses typically present in the hand (although they are found elsewhere also) with localised swelling with or without pain. They are slow growing.
Typically they present in 3-5th decades and have a slight female predilection with a M:F ratio of 1.5 -2.1:1 .
They have been divided macroscopically into localised or diffuse forms, and appear as rubbery multinodular masses that are well circumscribed. They have an enveloping fibrous capsule, and the cut surface is variably coloured depending on the relative proportions of fibrous tissue, haemosidering and pigmented foam cells.
The tumour is histologically identical to pigmented villonodular synovitis (PVNS) and is composed of fibroblasts and multinucleated giant cells, foamy histiocytes and inflammatory cells on a background fibrous matrix.
As these masses arise from tendons, commonly of the hand, they may cause pressure erosions on the underlying bone. This is only seen in 10 - 20 % of cases. More commonly these masses arise from the palmar tendons. The mass itself is of soft tissue density. Calcification is uncommon.
Ultrasound is useful as it allows not only characterization of the lesion but also is able to demonstrate the relationship with the adjacent tendon.
These masses are typically homogeneously hypoechoic, although some heterogeneity my be seen in echo-texture in a minority of cases . Most will have some internal vascularity.
Not surprisingly, given the histological similarity to PVNS, giant cell tumours of the tendon sheaths also share the same finding on MRI, mainly on account of hemosiderin accumulation.
* T1 :
o low signal
o variable enhancement
* T2 : low signal