What is Tenosynovial Giant Cell Tumour

Tenosynovial giant cell tumour is a non-cancerous, soft tissue growth, arising around joints of hands, fingers and lower extremities.¹ It usually presents as a small, painless swelling associated with joints. There are two subtypes with slightly different outcomes.² The main treatment is resection by surgery. This tumour, although generally benign, can recur after resection and rarely turns cancerous³

Overview

Tenosynovial giant cell tumour arises from a thin tissue covering around joints called the synovium. Synovium is a thin layer of tissue that is present around joint surfaces and contains a fluid called synovial fluid that protects joints and facilitates movements.

Tenosynovial giant cell tumours are also known as giant cell tumours of tendon sheath.⁴ In the past, they used to be called pigmented villonodular synovitis but this terminology is no longer used or accepted. There are two main subtypes, localized and diffuse. These two subsets have slightly different outcomes.

What causes tenosynovial giant cell tumour?

The exact cause of the tenosynovial giant cell tumour is not known. There are several presumed causes such as trauma, lipid disorders, immunity deficits etc. The current most believed theory is that this is a reactive growth or hyperplasia secondary to some inflammatory process.

Are giant cell tumours very large tumours??

Despite the name, the tumour doesn't mean a giant growth. It is the type of cells in the tumour which when sampled and seen under the microscope is bigger than surrounding cells and these cells are known as giant cells. These cells do not necessarily mean a bad come or cancerous outcome either as they can be present in reactive and inflammatory conditions.¹ 

Is tenosynovial giant cell tumour cancer?

The word tumour simply means growth. Tenosynovial giant cell tumours are usually benign, meaning non-cancerous but they can very rarely turn cancerous or malignant.

Who gets tenosynovial giant cell tumour?

It is usually adults who get tenosynovial giant cell tumour. The peak age range is around the 3^rd to 5^th decade. There are two subtypes called localized and diffuse, and both are reported to be more common in those who are assigned female at birth (AFAB) than those who are assigned male at birth (AMAB).

Where does tenosynovial giant cell tumour occur?

The location of this tumour depends on its subtype:

• Localised subtype usually occurs in the hands and fingers
• Generalised subtype occurs in the lower extremities and big joints 

Presentation of tenosynovial giant cell tumour

Signs

These tumour nodules are said to arise more commonly in the volar aspect or in other words palm side of the hand. Also, they seem to be more common in the finger joints towards the end of the fingers(distal) rather than those close to the wrist.² In those close to the wrist, the skin may be freely mobile over it while in the further ones near the fingertip, the skin tends to be attached to the lesion. If you shine a small torch into the lump it will not transilluminate, unlike a cyst which will, since the latter is a fluid-filled cavity.⁵

Symptoms Tenosynovial giant cell tumour usually presents as a skin coloured, swelling around the jointsof fingers, hands, toes or large joints. These are nearly always  and painless in the localised subtype and rarely can cause some distal numbness. Distal type tends to be painful and persist for a long duration as well as interfere with movements of the joint.¹ Some reports claim that there can be pain with increased physical activity.⁶

Limitations of joint movement can also occur secondary to these tumours.

Diagnosis

Your doctor may take a detailed history and do a physical examination.

Investigations include 

• Imaging– This is usually with ultrasound scans or MRI scans. These will show a soft tissue mass that is connected to a tendon and often does not move when the joint is flexed or extended.¹ The features of the mass would show that it’s solid and not cystic. Rarely erosion into underlying bone can be seen, usually in those occurring in feet.⁶
• Biopsy– The sampling of tissue from the tumour, is called a biopsy, It will then be processed in the lab and will show typical features of this tumour under microscopy.

Treatment 

Complete surgical resection is usually curative. However, if it is left behind, the tumour can recur. There is a place for some medical treatment lately, especially in cases where a patient is not fit to undergo surgery.

The diffuse type tends to be a bit more difficult to resect surgically and tends to recur.⁸

Sometimes radiotherapy is used as an adjuvant therapy to kill the tumour cells This is reported to have some success, especially in reducing the recurrence of the diffuse subtype, mostly in cases where the synovium has been only partially removed by surgery (partial synovectomy).²

A new drug called Pexidartinib has been introduced and approved lately by the FDA. This drug is said to block some immunity reactions and mediators and help prevent the growth of tumour cells ⁵

Outcome 

The outcome is generally reported to be good if surgically removed completely. However, attachment of the tumour to tendons appears to make complete resection difficult leading to recurrences. The diffuse subtype also appears to be harder to resect with a tendency to recur. There have been rare reports where the tumour has spread to other organs after repeated recurrences. These organs include the lungs and lymph nodes.²

Conditions that appear similar to tenosynovial giant cell tumour 

Some other conditions closely mimic tenosynovial giant cell tumours and these are:

• Ganglion cyst 
• Desmoid tumour 
• fibroma/fibrosarcoma
• glomangioma

Prevention of tenosynovial giant cell tumour

Since the specific cause for this tumour is not found it is difficult to identify a strategy to prevent it. Noticing any lumps around your joints and their growth and getting medical attention quickly is the best method for a good outcome.

FAQs

How common is tenosynovial giant cell tumour?

It is reported that in about one million population there will be 40 patients.¹ This tumour is also said to be the second most common soft tissue tumour of the hand, being second to another benign lump called a ganglion.⁶

Does tenosynovial giant cell tumour have a genetic basis or defect?

Tenosynovial giant cell tumour localized type is said to carry a translocation in the CSF-1 gene. This means a mix-up of genetic material within a known gene/s. The diffuse type is also said to have CSF-1 gene overexpression.1 Loss of the gene CDKN2A/B can be seen in the malignant version of this tumour.1 

Can the tenosynovial giant cell tumour turn cancerous later?

This tumour can rarely turn cancerous and a few reported cases are found in literature.⁷ These limited studies have confirmed the aggressive behaviour of the malignant version of these tumours and also confirmed their origin from the cells in the synovium.What are the newer treatments that are coming up for tenosynovial giant cell tumours?

A few newer treatments like tyrosine kinase inhibitors and CSF-1R inhibitors are being tried with variable success.^1,2

Summary

Tenosynovial giant cell tumour is a soft tissue tumour that grows around joints in hands and feet and is commonly non-cancerous through rare cancerous cases are reported. These tumours present as painless swellings around joints that can be diagnosed with scans and sampling. Complete resection by surgery is curative with some medical therapy and radiotherapy also available for use. This is the second most common soft tissue tumour of the hand and has a good outcome.