Intramuscular Baker's Cyst in Plantaris: A Case Report

Baker's cyst is found as most frequent cystic mass around the knee occurring between medial head of gastrocnemius muscle and semimembranosus muscle. The proximal or posterolateral extension of the cyst had been rarely reported and the cyst into the surrounding muscular tissue extremely rare. Intramuscular Baker's cyst that we report was found between lateral head of gastrocnemius muscle and popliteus tendon, and then extended into the plantaris muscle. With review of the literature, we here report a very rare case of plantaris muscular extension of Baker's cyst.