An unusual presentation of infected popliteal cyst without any underlying systemic manifestations or septic arthritis

A Popliteal cyst, also called a Baker’s cyst, is a benign, fluid-filled cyst that forms around the posterior knee joint. These cysts are commonly associated with septicemia or septic arthritis. The cyst generally forms between the medial head of the gastrocnemius and the semimembranosus muscles. The highest prevalence is usually seen in adults with degenerative arthritis. In children, it is seen at the age of 4-7 years with a herniated posterior knee joint synovium/capsule. Incidence increases with age. In adults, the cyst is often associated with degenerative diseases or meniscal injury, which can complicate the diagnosis. However, an infected Baker cyst without any systemic manifestations or underlying septic arthritis is a rare clinical entity. Here, we present a case of a female with no known underlying conditions or source of infection/trauma who presented with pain, swelling, redness and warmth of the left lower limb. Radiologic studies revealed an infected baker’s cyst without any underlying systemic manifestations. She was conservatively managed. Most of the baker’s cysts are left unidentified, a proper diagnostic work-up is needed for early intervention. In this case, we highlight the appearance of an infected baker’s cyst with a previous history of osteoarthritis and with no evidence of underlying septic arthritis. The patient was conservatively managed with no surgical intervention.