Abstract

Ganglion cysts are commonly seen tumor-like lesions that do not have synovial capsules and can have internal septae as well as fluid rich with hyaluronic acid and other mucopolysacharides. They can be seen anywhere in the body. Although their etiology remains unclear, it is thought that chronic irritation, chronic repetitive injury and chronic ischemia are factors involved. When symptomatic, they cause pain and local soft tissue swelling. Ganglia are traditionally classified by the tissue from which they originate, such as intraarticular, extraarticular, intraosseous, periosteal etc. Although ganglion cysts are a commonly seen pathology, intratendinous ganglion cysts are rarely observed and hard to clinically diagnose. Diagnosis is made by ultrasonography (USG) or by MRI (Magnetic Resonance Imaging) work ups. On MRI, they appear as well demarcated and lobulated masses originating from tendons, ligaments, tendon sheaths, meniscuses or joint capsules, giving out simple or complicated fluid signals, and they appear with a peripheral rim pattern when contrast agents are applied. On ultrasonography and doppler ultrasonography, they appear as hypoechoic or anechoich masses of no vascularization, with a lobulated outline and possibly an internal septa. In this publication, the intratendinous ganglion cyst on the semimembranous tendon of the knee joint as well as the related ultrasound-MRI findings and the pathologies which can be on its differential diagnosis are presented as a case study. To the knowledge of the author of this paper, this is the third published case study about ganglion cysts originating from the semimembranous tendon itself. It is necessary to consider these cysts in differential diagnosis in light of adequate radiologic data, as a rare cause of knee joint pain.

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