The Presence of Brucella in a Baker Cyst, a Case Report in Jeddah, Saudi Arabia- A Case Report

Bakers (popliteal) cysts are cystic masses that arise from bursae swellings filled with synovial fluid. It is assumed that preceding osteoarthritic or meniscal injuries cause the synovial fluid to extrude and concentrate, forming a gel-like material within a cyst. Clinical presentation is either symptomatic or asymptomatic swelling. The following symptoms are commonly associated with this condition: Knee pain, stiffness, and limited knee range of motion. Based on symptomatology and etiology, the management plan can be divided into conservative versus surgical intervention, by either decompression or excision. In most cases, baker cysts are not associated with infections. However, in our case report, we found that the patient had a positive Brucella culture in a symptomatic baker cyst.

This is an 84-year-old gentleman, who is known to have diabetes, hypertension, dyslipidemia, and heart disease presented to the emergency medicine department with complains of knee pain and swelling. The patient mentioned a recent ingestion of unpasteurized milk and a positive history of brucellosis infection years ago. The knee aspiration of the cyst resulted in a positive Brucella culture. The treatment involves eradicating the infection with intravenous antibiotics and then decompressing or excising the cyst, depending on the patient's clinical symptoms. Regarding our management approach, the patient underwent a conservative management with intravenous antibiotics.

In comparison to other more common organisms, such as Staphylococcus aureus species, Brucella is rarely found in baker's cysts. However, as demonstrated in our case report, it is important to keep infections, as rare as brucellosis, in the differential diagnosis of baker's cysts to provide the most appropriate management for patients.