case_images: PMC10215558_01
case_images: (A) Photo of right knee swelling. (B) Sagittal T2-weighted images illustrating a synovial lesion in the suprapatellar bursa. The arrow indicates scattered low-signal intensity areas in the villous hyperplastic synovium, representing hemosiderin deposits. (C) Sagittal T1-weighted fat-suppressed images illustrating bone erosion in the anterior aspect of the medial femoral condyle.
case_images: fsurg-10-1075171-g001.jpg
case_images: PMC10215558_01_fsurg-10-1075171-g001.jpg
case_images: F1
case_images: A 3-year-old girl presented with a history of swelling and pain in the right knee without a history of trauma, for 2 years (Figure 1A). Magnetic resonance imaging (MRI) showed a large synovial mass posterior to the anterior patellar facet with femoral erosion (Figures 1B, C).
case_images: (A) Intraoperative arthroscopic pictures of bone erosion in the anterior aspect of the medial femoral condyle (arrow), which had been captured in MRI. (B) Intraoperative arthroscopic pictures demonstrating synovial proliferation (arrow) suggestive of pigmented villonodular synovitis. (C, D) Histology of the excised synovial tissue presenting characteristic PVNS features (immunocytochemistry CD68-positive).
case_images: fsurg-10-1075171-g002.jpg
case_images: PMC10215558_01_fsurg-10-1075171-g002.jpg
case_images: F2
case_images: After excising the synovium by using a motorized shaver, a well-defined yellow mass covered by the synovium was observed laterally adjacent to the distal patella (Figure 2A). The diseased synovium in the posterior chamber and posterior aspect of the tibial plateau was removed using the posteromedial and posterolateral approaches (Figure 2B). A histological examination of the nodule tissue exhibited synovial hyperplasia, foamy macrophages, spindle cells, multinucleated giant cells, and a considerable amount of hemosiderin deposits, which confirmed a diagnosis of PVNS (Figures 2C, D).
case_images: (A, B) MRI images at postoperative 12 months. Sagittal T2-weighted image and sagittal T1 fat compression image. Illustrating the disappearance of a cystic villous hyperplastic synovial lesion without recurrence, with a slight synovial thickening. (C) Photograph of a postoperative knee at 24 months.
case_images: fsurg-10-1075171-g003.jpg
case_images: PMC10215558_01_fsurg-10-1075171-g003.jpg
case_images: F3
case_images: MRI revealed no signs of recurrence (Figures 3A, B). At the second follow-up 24 months after the surgery, the child resumed her regular school life without reporting any knee pain (Figure 3C).