Intratendinous ganglion cyst of the first extensor digitorum communis tendon

A 52-year-old woman presented with a 4-year history of a palpable and painless mass in the dorsum of the right wrist. She had no history of trauma, and she didn’t refer pain or inflammation.

Ultrasonography revealed a well-defined anechoic mass, with internal septations, located within the first extensor digitorum communis tendon.

MR imaging was performed obtaining T1-weighted images and T2-weighted images on sagittal and axial planes. The scan demonstrated a well-demarcated fusiform cystic lesion located between the fibres of the first extensor digitorum communis tendon. Some internal septations were observed. No signs of haemorrhagic of inflammatory complication were found.

Background

Ganglion cysts are benign lesions that arise in collagenous tissues due to mucinous degeneration produced by persistent irritation, recurrent damage and ischaemia [1]. They are filled with mucinous fluid rich in hyaluronic acid and other mucopolysaccharides, surrounded by dense connective tissue, and lack synovial epithelial layer [1,2].

They are the most common cause of palpable lesions of the hand and wrist [3]. They are traditionally classified according to their origin: tendon sheath, joint, bone or soft tissue. The incidence of an intratendinous ganglion cyst that originates within the tendon substance itself is relatively rare [1].

Clinical Perspective

Ganglion cysts usually present as an asymptomatic palpable mass. Occasionally, depending on their size and location, they may cause pain and mass effect [1]. Due to the rarity of the intratendinous location, it is difficult to suspect it fully based on the physical examination.

Imaging Perspective

Imaging plays an essential role in determining the composition of the palpable mass and its specific location. MRI and ultrasound are highly sensitive and specific methods for determining the cystic nature of the lesion, its size, location and relationship to the surrounding structures [1,3].

Ganglion cysts appear as well-demarcated rounded lesions, filled of fluid and often with sharply defined internal septations. On ultrasound, they appear as a well-defined anechoic mass with posterior acoustic enhancement due to its fluid composition [3].

On MRI they have homogeneous high-intensity signal on T2WI with a thin peripheral rim and often some internal septations. Intensity signal on T1WI is variable, being hyperintense if they have higher proteinaceous or haemorrhagic content. After gadolinium administration, they may show enhancement of the peripheral rim and septations, with no internal enhancement [2].

They might complicate with bleeding or inflammation. Haemorrhagic cysts may show a more heterogeneous appearance with low or bright internal signal intensity depending on the evolution of bleeding. If inflamed or infected, they may have a thickened outer lining or internal septa, as well as some degree of pericystic oedema. However, they should not demonstrate internal enhancement after intravenous contrast administration [2].

Outcome

Surgical excision is usually the first-choice treatment and consists of en bloc resection of the affected tendon to reduce recurrence. Our patient decided to maintain an expectant attitude due to the lack of disabling symptomatology.  

Teaching Points

Intratendinous ganglion cysts are rare lesions with difficult clinical diagnoses. Therefore, ultrasonography and MR imaging are essential tools for determining the accurate diagnosis and planning the appropriate treatment. 

Written informed patient consent for publication has been obtained.