Abstract
Baker cyst is an abnormal enlargement of the gastrocnemius-semimembranous bursa behind the knee joint due to an exit of joint fluid. We herein report a rare case of giant Baker cyst in a rheumatic arthritic female patient. An MRI scan showed a complex, multiloculated cyst measuring 11.8 cm x 4.6 c, x 3.3 cm, arising from the left knee joint. Open surgical excision of the lesion was performed, and no recurrence was observed during the one-year follow up in the Rheumatology and Orthopedics Department. A natural tendency towards intermuscular extension is observed; thus, intramuscular extensions are rarely reported in the literature. To the best of our knowledge, no Baker cyst of such size has been operated in a rheumatoid arthritis patient.