Pigmented villonodular synovitis is a rare chronic joint lesion caused by the proliferation of its synovial membrane with the formation of nodular or villous outgrowths and articular mice. Disease is characterized by periodic, and then permanent, swelling of the joint and the appearance of pain in it. Diagnostic measures include blood tests for RF, ANF, CRP, radiography, pneumoarthrography, arthroscopy, diagnostic puncture of the joint and biopsy of the synovial membrane. Treatment consists in removal of the synovial membrane followed by irradiation of the joint.
Meaning
Pigmented villonodular synovitis was first described in 1941. It is observed mainly in young and middle-aged people. There are cases of the development of the disease against the background of rheumatoid arthritis. Morphologically, the basis is the slow growth of the synovial membrane of one, rarely several, large joints. The process can extend to the synovial lining of tendons and mucous bags.
The formation of nodular and villous outgrowths occurring in this disease is accompanied by the accumulation of hemorrhagic effusion in the joint cavity and the deposition of hemosiderin on the articular surfaces of the bones entering the joint with the development of reactive synovitis. The outgrowths of the synovial membrane on the leg can eventually separate from it, forming bodies freely located in the joint cavity, which, calcifying, transform into so-called “articular mice”. Prolonged course leads to the appearance of degenerative changes in articular cartilage, and sometimes to their erosion.
Causes
Etiological factors and the mechanism of development of pigmented villonodular synovitis are unknown. There are still disputes in rheumatology about the genesis of this disease. Previously, there was a generally accepted point of view that pigmented villonodular synovitis is a granulomatous inflammatory process in the synovial membrane (synovitis). Modern cytogenetic studies have revealed chromosomal aberrations and signs of atypical proliferation in the growing cells of the synovial membrane of the affected joints, which is a sign of tumor formation. Thus, most authors today tend to consider pigmented villonodular synovitis a benign slow-developing tumor process.
Symptoms
The gradual onset and slow progression of this disease is characteristic. The disease begins with a periodically occurring swelling in the joint caused by the accumulation of hemorrhagic exudate in its cavity. During the loads on the affected joint due to the infringement of the outgrowths of the synovial membrane, pain may occur. Over time, swelling in the joint and arthralgia become permanent. Movements in the joint with pigmented villonodular synovitis persist in full for a long period, then stiffness gradually arises and increases. In some cases, periodic “blockages” of the joint are observed, indicating the presence of a “joint mouse”.
In 80% of cases of pigmented villonodular synovitis, the knee joint is affected. In the remaining 20% of cases, changes are observed from the ankle, hip, heel-cuboid joints. The defeat of the synovia of the mucous bags is manifested by a picture of bursitis and is most often found in the ankle joint. Involvement of the synovial membrane of the tendon sheaths leads to the development of tendovaginitis and is usually observed in the tendons of the flexors and extensors of the hand.
The general condition of patients with this disease, as a rule, is not disturbed. Body temperature is normal.
Diagnostics
To diagnose pigmented villonodular synovitis, a rheumatologist conducts a comprehensive examination of the patient with an assessment of laboratory blood parameters, X-ray and arthroscopic data, the results of the study of synovial fluid and the tissue structure of the synovial membrane sample.
For pigmented villonodular synovitis, inflammatory changes in the clinical blood test, the presence of C-reactive protein, ANF or rheumatoid factor are not characteristic. During joint radiography, in some cases, osteoporosis of the articular surfaces and some narrowing of the articular gap can be observed. Sometimes there are marginal erosions of the bony articular surfaces and cyst-like formations of the epiphyses. Pneumoarthrography often detects filling defects in the synovial membrane of the joint, having a rounded shape and multiple character. They correspond to the place of formation of giant nodes or villi of the expanding synovial membrane.
During the puncture of the joint with pathology, a synovial fluid colored red-brown is obtained. Her study reveals a large number of red blood cells, inflammatory changes are usually absent.
The most informative method of diagnosing pigmented villonodular synovitis is arthroscopy. It allows you to see the thickening and dark pink staining of the synovial membrane, brown villous and nodular outgrowths growing into the joint cavity, freely located detached nodes and villi, darkened articular cartilage. The brown and pink coloration of the synovial membrane, as well as the darkening of the cartilages, are associated with their hemorrhagic impregnation and deposition of hemosiderin. During arthroscopy, a synovial membrane biopsy is taken. Histological examination of the material in patients with pigmented villonodular synovitis reveals nodular proliferation, the presence of hemosiderin deposits and multinucleated giant cells.
Differential diagnosis of pigmented villonodular synovitis is carried out with intermittent hydrarthrosis, hydroxyapatite arthropathy, arthritis of various etiologies: rheumatoid arthritis, reactive arthritis, arthritis with tuberculosis, psoriatic arthritis, etc.
Treatment and prognosis
Treatment of pigmented villonodular synovitis consists in surgical excision of the overgrown synovial membrane — synovectomy, which can be performed by open access or using arthroscopic techniques. To prevent the recurrence of the disease, in most cases, postoperative radiation therapy of the affected joint is recommended.
The prognosis of pigmented villonodular synovitis is generally favorable, but the percentage of recurrence of synovial membrane growths after its surgical removal is quite high and accounts for about 20-30% of cases of the disease.