Introduction:

Baker’s cyst, also known as popliteal cyst, is the most prevalent cyst lesion around the knee joint. When symptomatic, it presents as a progressive discomfort in the popliteal fossa and a palpable oval mass. However, the rupture of a Baker’s cyst leads to acute pain and edema of the knee and midcalf. This case report aims to alert the general practitioner to the diagnosis of a ruptured Baker’s cyst, its important clinical findings, and its main differential diagnosis, in order to correctly approach these patients.

Case report:

This case report is about a 46-year-old man who presented to the emergency department due to right lower limb pain, edema, and ecchymosis. The final diagnosis was a ruptured Baker’s cyst which was managed conservatively. The main differential diagnosis was deep vein thrombosis (DVT).

Comment:

Baker’s cyst rupture is one of the complications of this popliteal cyst, which happens more often in patients with underlying inflammatory knee disorders. On physical examination, Baker’s cyst rupture may present with lower limb edema, pain, and ecchymosis (crescent sign). Hence, its presentation may mimic DVT, which is why Baker’s cyst rupture is also known as pseudo-thrombophlebitis. Despite rare, the crescent sign is not present in DVT, thereby supporting a recent Baker’s cyst rupture. This case report highlights the importance of a clinical suspicion concerning a ruptured Baker’s cyst in patients presenting with unilateral pain and edema of a lower limb, especially in the presence of clinical findings such as the crescent sign.

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