Pigmented villonodular synovitis of the shoulder and knee in a child: a rare presentation of an uncommon pathology

Abstract

BACKGROUNDPigmented villonodular synovitis (PVNS) is a rare benign disease, with an estimated prevalence of 1.8:1,000,000 people. It occurs by proliferation of the synovial membrane of the joints, bursae and tendinous sheaths, with pigmentation by hemosiderin deposits. It mainly affects individuals between the ages of 30 and 40. It affects the knee in about 80% of the cases and is extremely rare in the shoulder. Less than 3% of all PVNS cases are reported to occur in the shoulder, with fewer than 50 cases reported in the literature to date. CASE REPORTThis study followed the case of an 11-year-old girl had a 6-year history of increasing pain and swelling in his right knee and no history of trauma. After 2 years of follow-up, she developed arthritis in the left knee and 1 year after pain and swelling in the right shoulder. The child's mother reports that her daughter has hydrocephalus and patent foramen ovale without hemodynamic repercussions. A physical examination of the patient revealed swelling in the right shoulder without limitation in range of motion and swelling and joint effusion in both knees. The patient was treated with deflazacort and methotrexate for a few months in response to signs and symptoms were very similar to juvenile idiopathic arthritis (JIA). However, the arthritis did not improve. Due to lack of improvement with treatment and the recurrent arthritis in the knees and swelling in the right shoulder, further laboratory tests were requested and the results did not suggest that the patient had JIA. Plain radiographs showed normal bone structure, but magnetic resonance imaging showed a joint effusion with diffuse synovial thickening in the knee and increased joint fluid and thickening of the synovial membrane in the right shoulder. The patient underwent arthroscopic synovectomy. Histologic examination of the tissue exposed hyperplasia of the synovium, multinucleated giant cells and a considerable amount of hemosiderin deposits, based on which the patient was diagnosed with PVNS. The patient was referred to orthopedics for knee and right shoulder synovectomy. CONCLUSIONAlthough PVNS is a rare condition in pediatric patients, it can occur with symptoms resembling JIA. Adults may rarely develop PVNS in multiple joints. Children may also develop polyarticular disease. Most of the children with polyarticular disease have other congenital problems suggesting a possible genetic basis for this syndrome.