Villous pigment nodule synovitis is a proliferative lesion of the synovium, which often presents as localized nodules. The mass may originate from the synovium of the joint, the sheath of the tendon, the fascial layer, or the ligament tissue. The lesion presents as painless soft tissue mass, usually located on the fingers and toes. It can also be seen in other joints (especially the knee joints) and sheaths. Monarticular onset is a regular feature of the disease, but there are also rare cases of polyarticular lesions. The lesion presents as painless soft tissue mass, usually located on the fingers and toes, and can also be seen in other joints (especially the knee joints) and sheaths. Monarticular onset is a regular feature of the disease, but there are also rare cases of polyarticular lesions. Clinically, it often presents as painless joint swelling or mild pain with swelling. Acute joint pain and swelling may occasionally occur. Patients may also experience symptoms such as joint locking. The etiology of this disease is unknown, and it is generally considered a reactive lesion.
Difficult-to-explain hip pain in young patients should be considered as a possibility of villous pigment nodule synovitis. Villous pigment nodule synovitis has two forms: diffuse and nodular. The nodular form is most common in the hands, while the diffuse form is most common in the knee joints. Villous pigment nodule synovitis can also occur in other joints such as the hip joint, ankle joint, and elbow joint. In the past, it was considered a malignant lesion, but it has now been confirmed as a benign lesion, which is mostly considered a chronic inflammation of the synovial tissue. Therefore, surgical treatment is not easy to completely remove and often recurs.