case_images: PMC11513652_01
case_images: Anteroposterior X-ray showing a soft-tissue mass in the left knee. The arrows indicate the increased soft-tissue shadow in the left knee.
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case_images: Initial radiographs showed a soft-tissue mass in the left knee (Fig. 1).
case_images: Axial MRI of the right knee demonstrating diffuse intra-articular pigmented villonodular synovitis (PVNS). (A) T2-weighted image showing a multinodular lesion with low signal intensity due to the presence of hemosiderin deposits. The lesion is characterized by diffuse synovial thickening and irregular nodular areas. (B) T1-weighted, fat-saturated postcontrast sequence revealing enhanced synovial proliferation with marked contrast uptake indicating active disease. The arrows highlight the extent of synovial thickening and nodularity, with hemosiderin deposits visible as areas of low signal intensity.
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case_images: T1-weighted images. The MRI also showed synovial thickening and postcontrast enhancement, consistent with active synovial proliferation. These findings, combined with hemosiderin deposits and mild joint effusion, confirmed the diagnosis of diffuse PVNS (Fig. 2).
case_images: Perioperative images of the open approach synovectomy. (A) Anterior approach; superficial dissection. The arrow indicates the macroscopic appearance of the synovitis. (B) Anterior approach; exposure of the PVNS. The stars indicate the villonodular synovitis, which appears as a chamois yellow. (C) Anterior approach; results after anterior synovectomy. (D) Posterior approach; superficial dissection. (E) Posterior approach; exposure of the popliteal neurovascular bundle (indicated by the arrow). (F) Posterior approach; posterior synovectomy. The star indicates the exposed synovitis prepared for resection.
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case_images: This procedure included a large anterior approach for intra-articular synovectomy, followed by a posterior approach (Fig. 3).
case_images: Axial MRI of the left knee demonstrating diffuse intra-articular Pigmented Villonodular Synovitis (PVNS). (A) T2-weighted multi-echo gradient image showing a multinodular lesion with low signal intensity due to hemosiderin deposits. The image reveals extensive synovial thickening and nodular formations, with the hemosiderin deposits contributing to the observed signal drop-out effect typical of PVNS. (B) T1-weighted, fat-saturated postcontrast sequence displaying enhanced synovial proliferation with marked contrast uptake, highlighting the extent of synovial thickening and nodularity. The stars indicate the villous and nodular lesions, which are prominent due to the contrast enhancement and low signal intensity areas from hemosiderin deposits.
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case_images: Radiographs and MRI revealed lesions consistent with diffuse PVNS (Fig. 4).
case_images: Perioperative images of the open approach synovectomy of the right knee. (A) Anterior approach; the black arrow indicates the pigmented villonodular synovitis; the white arrow indicates the cartilage of the lateral femoral condyle. (B) Posterior approach; the star indicates the intra-articular Pigmented Villonodular Synovitis. (C) Excised synovial tissue.
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case_images: PMC11513652_01_gr5.jpg
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case_images: Surgical intervention was performed to completely remove these lesions (Fig. 5), and histological analysis confirmed the diagnosis.