RESUMO
Baker's cysts, commonly incidental findings, can occasionally present as intramuscular dissecting cysts within the medial gastrocnemius muscle. This case report highlights the ultrasound features and differential diagnoses of intramuscular dissecting Baker's cysts through the examination of three distinct cases: a 64-year-old woman with severe osteoarthritis, an 80-year-old man with a palpable mass in the popliteal fossa, and a 37-year-old man with early degenerative arthropathy. Each case was investigated using ultrasound, revealing fusiform hypoechoic fluid collections with heterogeneous echostructure parallel to the medial gastrocnemius muscle bundle and lacking posterior reinforcement. The clinical context and ultrasound findings were critical in differentiating these cases from other conditions, such as superficial thrombophlebitis, intramuscular seroma, and intramuscular myxoma. These cases emphasize the role of ultrasound in diagnosing intramuscular dissecting Baker's cysts. Accurate diagnosis requires careful consideration of ultrasound features in conjunction with clinical findings.