PMC7210901_01
(a) Clinical picture showing swelling of knee joint. (b) per-operative image showing yellow-colored hyperplastic synovium thrown in finger-like projections.
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F1
An 8-year-old girl presented to the orthopedics OPD with swelling and pain in the left knee for the past 6 months (Fig. 1a). Intraoperatively, the synovium appeared markedly hyperplastic, yellowish in color, and extending into the supra and infrapatellar compartments of the knee (Fig. 1b).
(a) X-ray showing a lytic lesion in the proximal tibial epiphysis with peripherally placed sclerotic areas. (b) Magnetic resonance imaging of the knee joint showing a heterogeneous lesion in the tibial epiphysis, synovium having villous architecture, and same signal intensity as that of fat.
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F2
X-ray of the knee joint was advised which showed a lytic lesion in the proximal tibial epiphysis with peripherally placed sclerotic areas (Fig. 2a). X-ray did not reveal any significant joint effusion and in view of marked joint swelling, a magnetic resonance imaging (MRI) of knee joint was done. The MRI showed a heterogeneous lesion in the tibial epiphysis with altered signal intensity and a sclerotic rim (Fig. 2b).
(a) Microscopically, villous and nodular projection of synovium with replacement of stroma by adipose tissue (Hematoxylin and Eosin, x40). (b) High power view shows hyperplasia of synovial lining with proliferation of adipocytes and chronic inflammation (x400). (c) Tumor showing lobules of cartilage with chondroblasts showing chicken wire calcification (Hematoxylin and Eosin, x100). (d) High power shows nuclear molding with grooves.
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F3
Sections from the synovial tissue showed villi-like proliferations of the hyperplastic synovium with expansion of the subsynovium with mature adipose tissue (Fig. 3a and b) and also seen were interspersed chronic inflammatory cells and few dilated vessels. A chicken-wire matrix surrounding the chondroblasts was seen (Fig. 3c and d).