Meniscal cyst causing periarticular tibial erosion.

Meniscal cysts causing bone erosions are rare. The majority of meniscal cysts are associated with tears of the menisci and magnetic resonance (MR) imaging appearances are usually diagnostic. The MR images of a 34-year-old man showed a well-defined cystic mass that communicated with a horizontal cleavage tear of the posterior horn of the lateral meniscus and caused pressure erosion of the lateral tibial condyle. We believe this to be the first locally reported case of tibial erosion related to a meniscal cyst. This entity should be included in the differential diagnosis for a well-defined periarticular erosion.