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Pigmented villonodular synovitis in a rare site

Pigmented villonodular synovitis (PVNS) is a rare locally aggressive benign proliferative growth of the synovium of unknown etiology known to involve the knee (80%), hip (10%), ankle (5%), and exceptionally temporomandibular joint and spine. It poses a diagnostic dilemma when it occurs at the ankle with the clinician tending to overlook it like an ankle sprain or posttraumatic pathology. The optimal treatment is surgery. Malignant change of the lesion, although rare is known for its ability for reactivated growth and a tendency to recur. Postoperative radio synoviorthesis may be required to remove the excess synovium when surgery alone falls short of removing the residual synovial membrane. This article reports the case of a rare localized PVNS of the ankle. Although rare at the ankle, PVNS must neither be mistaken for a malignant lesion nor be neglected as a nonspecific swelling.