660 - Hemorrhagic Conversion of Ganglion Cyst

A 39-year-old male presented to the clinic with three weeks of left leg pain and swelling after traveling from New York to Japan. Patient was evaluated in Japan where a deep vein thrombosis could not be excluded as no ultrasound was available. They prophylactically administered rivaroxaban for 3 days followed by aspirin 100 mg daily. The swelling worsened after a subsequent flight to Australia, leading to a duplex ultrasound which was negative for clots. Symptoms began improving until the patient received a deep tissue massage, and experienced a subacute worsening of the symptoms. 

Patient was referred to a sports medicine clinic where ultrasound revealed a 6cm wide fluid collection of mixed echogenicity and floating debris within the gastrocnemius-semimembranosus bursa. MRI revealed hemorrhagic conversion of a ruptured popliteal cyst measuring 18.1cm by 4.6cm. The patient experienced significant symptom relief with physical therapy, compression stockings, and aspiration of the cyst.

Discussions: We present an interesting and rare case of hemorrhagic conversion of a ganglion cyst. There are few reported cases of hemorrhagic conversion of a ganglion cyst in the posterior knee, and subsequently there are no treatment guidelines for its management. Additionally, the size of the cyst was large considering the lack of significant intra-articular knee pathology according to the patient’s imaging. Ultrasound proved to be essential in both diagnosing and monitoring the swelling over time. Physical therapy, compression stocks, and aspiration of the cyst then played an instrumental role in helping the patient return to previous activities and in preventing re-rupture of the cyst.

Conclusions: In patients with acute onset leg pain with swelling, hemorrhagic conversion of a ganglion cyst is important to include on the differential in addition to deep vein thrombosis.