PMC9826551_01
Pre-operative plain radiographs of the ankle. (a) Anteroposterior radiograph shows diffuse swelling of the ankle and irregular inferior border of tibial plafond suggesting anterior tibial osteophytes. (b) Lateral radiograph shows osteophytes at the anterior distal tibia and dorsal talar neck with preservation of the tibiotalar joint space. Furthermore, lateral radiograph shows in posterior ankle recess os trigonum (arrow) and disturbance in anteroinferior corner of Kager's triangle due to soft-tissue mass (arrowhead).
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F1
Standard anteroposterior (AP) and lateral (LL) radiographs (Fig. 1) showed diffuse swelling of the ankle and osteophytes of the anterior distal tibia and dorsal talar neck.
Pre-operative magnetic resonance imaging (MRI) of the ankle. Pre-operative fat-suppressed proton-density-weighted MRI sequences of the ankle. MRI images in (a) sagittal, (b) coronal, and (c) axial plane show low signal intensity soft-tissue mass in the posterior ankle recess encircled by high signal intensity zone (arrow).
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F2
Magnetic resonance imaging (MRI) of the ankle was performed to evaluate the soft-tissue mass (Fig. 2).
Arthroscopic view of localized pigmented villonodular synovitis in the posterior ankle recess. Arthroscopic view of the posterior ankle recess from the posteromedial portal shows (a) pedunculated well-encapsulated soft-tissue mass with yellow and brown pigmentation, and (b) a radiofrequency wand, placed through posterolateral portal, in contact with pedicle of a soft-tissue mass.
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F3
It was cut from the stalk with a radiofrequency wand and the mass was removed from the joint with a grasper (Fig. 3).
Histopathological images of the soft-tissue mass removed during hindfoot endoscopy. Hematoxylin and eosin-stained slide with original magnification x4 (a) and x10 (b). The lesion histologically displayed a fibrohystiocytic stroma with randomly dispersed multinucleated giant cells, some siderophages and diffuse infiltration by macrophages, foamy macrophages, and lymphocytes confirming the diagnosis of localized pigmented villonodular synovitis.
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Histopathological analysis confirmed that nodular mass found in the posterior recess of the ankle was indeed a LPVNS (Fig. 4).