Pigmented villous nodular synovitis is relatively rare, and there are two types: villous and nodular. Patients are mostly young and middle-aged men. They are mostly between the ages of 20 and 40. The disease is more common in the knee and ankle joints, followed by the hip, intertarsal, wrist, elbow and occasionally the bursa and tendon sheath.
Etiological evidence
The disease is probably a synovial disease between inflammation and benign neoplasm. The villous form is more closely resembling an inflammatory disease. Animal studies have demonstrated that repeated injections of blood into the joint cavity can produce the same pathological changes as the villous form. Similar changes may be seen in athletes with repeated knee bleeding. The nodular form is composed of a large number of synovial cells and is prone to recurrence if not completely excised, thus resembling a benign tumor.
Morphology
The affected synovial membrane is dark red or brownish yellow in the villous type, and is often significantly thickened, up to 1 cm or more. The synovial surface is uneven, often with folds and villi. Some of the villi are long and thin, up to 1 to 2 cm long, and float in the water like whiskers; others are short and fuse with each other to form nodules. The diameter of the nodules ranged from 1cm to 4-5cm. Smaller nodules were reddish brown, while larger nodules were yellowish white with rusty spots. The nodules are slightly stiff and tough, and swirling fibrous tissue is seen on the profile, with occasional mucus degeneration and fissures. In some cases, there are both villous and nodular lesions.
The distribution of lesions can be classified as diffuse or limited. Diffuse lesions are more common, and a few are limited. In diffuse lesions, villous and villous-nodular lesions are common, and in limited cases, they are usually nodular.
Pathological changes
Microscopically, the surface of the villi is composed of several layers of synovial cells with a few fibrous tissue, dilated capillaries and a few inflammatory cells in the center. Iron-containing hemosiderin granules can be seen inside and outside the cells. The nodules consisted of dense synovial cells with little cytoplasm, indistinct cytosol, and dark nuclear staining. Fissures and papillae were seen in the dense cells. Multinucleated giant cells and foam cells are occasionally seen between the synovial cells.
Symptoms
Clinical manifestations
The disease has no obvious systemic symptoms. The patient’s body temperature is not high, the blood sedimentation is not fast, and the blood picture is unchanged. The local symptoms are also mild in the early stage, so the patients are diagnosed late and the disease duration is long, generally 1-5 years is the most, and more than half of them have a history of trauma. The main symptom is joint swelling, pain is relatively mild, local skin temperature is sometimes slightly high, and joint function is not obviously limited. In diffusely swollen joints, the thickened synovial membrane is spongy to the touch, and fluctuating sensations can be palpated in cases of fluid accumulation. Sometimes nodules of varying size and slightly mobile can be palpated.
The suprapatellar bursa and patella are obviously swollen when the knee is involved, and the patella test is positive if there is a lot of fluid. The hyperplastic synovial tissue may sometimes penetrate the posterior joint capsule and enter the N fossa and spread down the posterior calf muscle space, producing a deep diffuse swelling. The swelling is most pronounced around the inner and outer ankles in ankle involvement. In the case of hip involvement, the swelling is mostly located anterior to the hip joint.
Whether diffuse or limited, there is mild muscle atrophy in the affected limb. Joint puncture may draw bloody or coffee-colored fluid, and this joint fluid is very specific and has diagnostic value.
Diagnosis
The diagnosis of this disease is usually not difficult when the clinical manifestations are carefully analyzed and combined with joint fluid and X-ray examination.
Examination
The examination methods for this disease are mainly as follows.
1. X-ray plain film signs of this disease include joint swelling and joint bone erosion and destruction. Soft tissue swelling is nodular with high density; PVNS bone erosion mostly starts at the junction of bone and cartilage, so the joint space generally remains normal. However, when the amount of joint fluid is high, the joint gap may widen; when secondary joint degeneration or articular cartilage suffers significant erosion, the joint gap may narrow.
2. CT is cross-sectional imaging with high density resolution, which is significantly better than X-ray plain film in showing soft tissue masses, joint effusion and bone erosion in the joint cavity, and more sensitive than X-ray plain film in showing the sclerotic margin around the bone defect; CT enhancement scan can show irregular thickened synovial membrane, which can help in the diagnosis of PVNS. However, CT lacks characterization for showing lesions of joint capsule, articular cartilage, and soft tissues, and is more meaningful when the lesions have significant bone erosion. Therefore, the diagnostic value of CT is limited in the early stage of PVNS or when there is no bone erosion.
The typical manifestation of PVNS is low signal in T1WI and T2WI, and the pathological basis of this feature is the deposition of iron-containing heme in the nodules. However, the early stage of the lesion shows only hemorrhage in the joint with no or little iron-containing heme deposition in the nodule, and the later stage of the lesion shows a decrease in iron-containing heme by absorption and transport. Therefore, this signal characteristic does not go through the whole course of the lesion.
4. Laboratory examination. Microscopically, the surface of the villi was composed of several layers of synovial cells with a small amount of fibrous tissue, dilated capillaries and a few inflammatory cells in the center. Iron-containing hemosiderin granules were seen inside and outside the cells. The nodules consisted of dense synovial cells with little cytoplasm, indistinct cytosol, and dark nuclear staining. Fissures and papillae were seen in the dense cells. Multinucleated giant cells and foam cells are occasionally seen between the synovial cells.
Treatment
The disease is treated by both surgical resection and radiation therapy.
Surgical treatment
1. Surgical excision is more complete and is particularly suitable for nodular type cases. Radiation therapy is better for the villous type and less effective for the nodular type. For diffuse lesions, all synovial tissue should be removed to avoid recurrence. For the knee joint with abundant synovial membrane, the synovial tissue in the front and back of the joint can be cut out as much as possible.
2, followed by radiation therapy after surgery, which can also achieve a cure. For diffuse nodular lesions, the knee ligaments and collateral ligaments should be cut and the joint dislocated, and then the anterior and posterior synovial tissues should be completely removed, because nodular lesions that are not completely removed are prone to recurrence, and a few cases are transformed into synovial sarcoma. For limited lesions, only the local synovial tissue can be removed.
Traditional Chinese Medicine Treatment
The key to treatment is to avoid weight-bearing and restrict activities. The child is asked to lie on his back, the operator stands on the affected side, holds the ankle with one hand and the knee with the other, first gently does hip flexion and knee flexion movement, and then shakes the hip without pain, and does hip flexion and internal rotation of the affected limb for long legs, and hip flexion and external rotation for short legs, followed by straightening the affected leg.
After the manual method is finished, give Dunhuang anti-swelling and analgesic cream to be applied externally, according to the size of the swollen part of the affected hip, cut a piece of plastic paper with fever particles that is 2-3mm larger than the part, apply Dunhuang anti-swelling and analgesic cream evenly on the plastic paper, 2-3mm thick, cover the affected part, fix it with adhesive tape, change the medicine once every 2 days. And instructed to rest in bed for 3-5 days during treatment.
According to Chinese medicine, this disease is caused by a small displacement between the femoral head and the acetabular fossa due to trauma, so it is called “pediatric hip joint misalignment” and belongs to the category of “paralysis”. The injury leads to poor flow of qi and blood, closed tendons and veins, or because the child’s form is not yet full of qi, liver and kidneys are not yet hyperactive, tendons and bones are not firm, easy to be invaded by wind, cold and moisture and other external evil, as the Suwen? Palsy” said: “wind, cold, damp three gas mixed to, combined for paralysis.” Wind, cold and dampness paralyze the veins and collaterals, stagnate the qi and blood, and cause pain if they do not pass; the pure yang body of children, the evil qi is easy to turn into heat from the yang, and the heat of the evil fights with each other, which is manifested as fever in the affected limbs; labor consumes qi and increases the stagnation of qi and blood in the meridians, and the tendons and flesh are constricted, resulting in impaired joint movement, so the child refuses to hold weight and limps. The Chinese medicine treatment for this disease is to invigorate blood circulation and remove blood stasis, and to promote the circulation of dampness.
Dunhuang Decongesting and Analgesic Cream is made from 10 selected herbs. This formula uses Wu Ming Yi as the ruler, the main gold sores, fractures, pain relief, muscle growth, to treat bone and bruise injuries as the main feature; supplemented by raw rhubarb to dispel blood stasis and invigorate blood, healing injuries and analgesia as the minister; safflower, chicken blood vine, yanhuo invigorate blood, move Qi and relax tendons, douhu and wei lingxian to benefit dampness and open the ligaments, together as the adjunct. The combination of all the medicines can move and disperse, which has a strong effect of activating blood stasis, moving qi and relaxing ligaments, reducing swelling and relieving pain. The use of external treatment in Chinese medicine is one of the effective methods for treating transient synovitis of the hip joint in pediatric patients.
Discussion
The pathogenesis of PVNS is unknown, but the main views are: local fat metabolism disorder, trauma, chronic inflammation of local synovium, and tumor-like degeneration, among which tumor-like degeneration has been accepted by most scholars in recent years, and it is believed that pigmented villous nodular synovitis is a benign tumor-like process, which is a tumor-like proliferation of synovial fibroblasts and histiocytes. into two types: diffuse and nodular.
PVNS is a chronic synovitis characterized by joint swelling and fluid accumulation, which is difficult to diagnose and treat. MRI is helpful but inconclusive in the diagnosis of PVNS. MRI is helpful but inconclusive for the diagnosis of PVNS. Arthroscopy plus pathology is required for definitive diagnosis. Differentiation PVNS should be differentiated from the following diseases: gout, a group of diseases caused by the increase of uric acid in the blood due to the disorder of purine metabolism, with redness, swelling, heat and pain in the joints, limited movement, accompanied by fever, chills, fatigue, anorexia, headache and other symptoms, gout stones can be formed, X-ray and blood tests can be differentiated; rheumatoid arthritis, which also starts in the synovial membrane, can be seen as swelling, fluid, muscle atrophy The difference between rheumatoid arthritis, which also starts in the synovial membrane and is characterized by swelling, effusion, and muscle atrophy, and is often multi-joint, with changes in blood sedimentation, rheumatoid factor, and blood picture, and pigmented villous nodular synovitis, which is usually seen in a single joint, with no changes in the above laboratory tests and a difference in joint aspiration; synovial tuberculosis, which is also characterized by swelling, effusion, and a chronic process, is easily distinguished by X-ray and joint aspiration.
When treating PVNS arthroscopically, careful intraoperative examination is required to first find the typical part of synovium for pathological examination, and then follow the sequence of intercondylar fossa – medial space – medial crypt – suprapatellar capsule – lateral crypt – lateral space -The synovial membrane should be shaved in the order of the posterior joint cavity, and the parts that are easily missed, such as the upper part of the posterior femoral condyle and the underside of the meniscus, should be cleared with attention and, if necessary, with forceps, for clean excision, and electrocautery can be given to prevent bleeding. Although postoperative radiotherapy can reduce the recurrence rate, radiotherapy may cause joint stiffness, slow wound growth and healing, especially in young people, the chance of sarcoma, etc. We believe that thorough removal of the diseased synovial membrane can achieve good results, one case of recurrence in this group of patients was caused by incomplete shaving. Postoperative rehabilitation is important, and early rehabilitation can lead to fast recovery of joint swelling, mobility and muscle strength.
Arthroscopic surgery is one of the effective treatment methods for PVNS. Arthroscopic treatment is as effective as incisional surgery, and arthroscopic subsurface resection is more effective than incisional surgery. There are many complications after incisional surgery, such as pain, joint swelling, and difficulty in flexion, and the surgical requirements for incisional synovial removal are high. Arthroscopic treatment can completely remove the synovial membrane in locations that cannot be reached by incisional surgery, and there is little damage, low recurrence rate and good functional recovery. Nodular PVNS has a very good follow-up prevention effect, and arthroscopic surgical treatment can be the first choice. Thorough removal of the diseased synovium is the key during surgery, and postoperative radiotherapy is not possible. Early postoperative rehabilitation is important for joint swelling and pain to subside and function to recover.
Differentiation
Pheochromocytic synovial nodules need to be differentiated from joint diseases that can lead to joint swelling, joint effusion, and joint bone destruction. Soft tissue swelling in pigmented villous nodular synovitis is dense and nodular and predominantly intra-articular, with no osteoporosis, sclerotic edges of bone defects, and the joint space remains normal to help differentiate from diseases such as joint tuberculosis, synovitis, synovial sarcoma, and rheumatoid arthritis. Calcification is mostly seen in tuberculosis and synovial sarcoma, but pigmented villonodular synovitis should not be completely excluded. Calcification should be analyzed in a comprehensive manner among all signs so as to reduce misdiagnosis.
1, Charcot’s joint: early all appear joint swelling, effusion, painless, etc., but most have a history of trauma, joint deformity is more serious. x-ray seen new bone formation, bone end disintegration, joint surface destruction, joint dislocation and other bone and joint damage is extremely inconsistent with clinical symptoms.
2, synovial sarcoma: both have soft tissue masses, calcification, bone destruction, but synovial sarcoma is fast developing, short duration, severe pain, bone destruction is dissolving, no sclerotic edge.
Synovial tuberculosis: Both have swelling of periarticular tissues, destruction of joint surfaces, and early widening and late narrowing of joint spaces. The difference is that tuberculosis has obvious osteoporosis, joint surface destruction involving both sides, no sclerotic edge, and no mass shadow in the soft tissue.
4, rheumatoid arthritis monoarticular type: mostly seen in the elbow, wrist, knee, finger joints, joint swelling, soft tissue thickening, pain is not very obvious. Early appearance of osteoporosis, joint space narrowing or even worm-like destruction. The joint is penetrated by clear fluid.
Prevention
The disease is mostly caused by the chronic effects of other diseases, such as athletes due to repeated knee bleeding, may also produce similar changes, so the prevention of this disease is the main prevention of joint injury, once the injury occurs, due to active treatment, early and correct diagnosis and treatment is an effective measure to improve the effectiveness and restore the function of the patient’s joints.
Complications
Dysplastic villous nodular synovitis is an idiopathic proliferative damage involving the synovial membrane, joint capsule and tendon sheath. In young patients, the entire synovial membrane is involved in the knee joint, and the tibial intercondylar ridge is eroded. In this case, a subchondral granuloma, 3 mm in diameter, resembling a tibial giant cell tumor is seen. Cortical destruction of the intercondylar fossa of the femur is seen in tomographic views. Diffusely pigmented villous nodular synovium is caused by the proliferation of large amounts of synovial tissue, resulting in increased intra-articular pressure. The villus easily invades the osteochondral cancellous through the articular cartilage, the junction of bone and joint, or along the ligament attachment.