As formidable as it sounds, the tenosynovial giant cell tumor is not malignant. But this group of rare tumors tends to develop in the joints, accompanied by their own set of problems. Although the tenosynovial giant cell tumor isn’t cancerous, it keeps growing and can damage the surrounding regions. These tumors tend to grow in three areas of the joint:

• Synovium
  The thin layer of tissue that lines the inner joint surfaces.

Types of tenosynovial giant cell tumor

This group of tumors is categorized on the basis of where these tumors are located and how fast they grow. The tumors of this group that are localized tend to grow slowly and often start in smaller joints like the hand; such tumors are called giant cell tumors of the tendon sheath, i.e., D-GCTS. Diffuse tumors that grow quickly and affect large joints like the knee, hip, ankle, elbow, or shoulder, are called pigmented villonodular synovitis, i.e., PVNS.

It is essential to note that both the localized and diffuse tumors can affect the inside of the joints (intra-articular) while diffuse tumors can be found outside the joints as well (extra-articular). In some rare cases, these tumors can spread to different sites like the lungs or lymph nodes.

Causes of tenosynovial giant cell tumor

The causes of the tenosynovial giant cell tumor can be traced down to the chromosomal level. It is caused by a change to the chromosome, which is called translocation, and it occurs when pieces of a chromosome break off and change places. Although it’s unclear what causes this translocation, it has been identified as the confirmed cause of the condition.

It is a known fact that chromosomes contain the genetic code for producing proteins, and this translocation triggers the excess production of a protein called colony-stimulating factor 1 (CSF1). This protein attracts cells that possess the CSF1 receptors on the surface and includes white blood cells called macrophages. Then, these cells go on to clump together until they form a tumor.

This condition tends to affect people in their 30s and 40s.

Symptoms of tenosynovial giant cell tumor

It is essential to recognize the symptoms of the condition as it helps in seeking timely treatment. These symptoms are

• Joint stiffness
• Swelling or a lump in the joint
• Pain or tenderness in the joint
• Warmth of the skin over the joint
• Sounds of locking, popping, or catching when the joints are stressed on