Choroidal nodular synovitis, known as pigmented choroidal synovitis, is a specific type of proliferative synovitis that causes joint swelling, fluid accumulation, pain, limited joint function, and mild muscle atrophy. If not treated early or repeatedly, the synovial membrane can become hypertrophic and erode the surrounding bone and cartilage, causing bone erosion and bone loss; the presence of a large amount of fluid in the joint can widen the joint space, leading to joint degeneration and limited limb movement. If the nodular lesions are not treated thoroughly, they may become synovial sarcoma. Patients should go to the hospital for X-ray, CT, MRI, and arthrocentesis for early diagnosis and treatment, or opt for surgical resection or radiation therapy depending on the situation.