# Pes Anserine Ganglion Cyst as a Rare Cause of Chronic Medial Knee Pain: A Case Report

## TL;DR

A rare case of a pes anserine ganglion cyst causing chronic medial knee pain is reported, highlighting the importance of MRI for diagnosis and successful surgical treatment.

## Contribution

This case report adds to the limited literature on pes anserine ganglion cysts as a rare cause of medial knee pain.

## Key findings

- MRI was crucial in identifying a multilobulated cystic lesion near the pes anserine bursa.
- Arthroscopic excision resolved the patient's symptoms with no recurrence at six weeks.
- The case emphasizes the need to consider this rare condition in differential diagnoses of medial knee pain.

## Abstract

Ganglion cysts are benign mucin-filled pseudocysts most commonly encountered in the wrist and hand, while intra-articular ganglion cysts of the knee are rare, particularly those arising near the pes anserine bursa. Their nonspecific presentation often overlaps with more common causes of medial knee pain, leading to diagnostic delay. We report the case of a 43-year-old woman who presented with progressively worsening, atraumatic medial knee pain over several months with a largely unremarkable physical examination. Plain radiographs were normal, while magnetic resonance imaging demonstrated a well-circumscribed, multilobulated cystic lesion adjacent to the pes anserine bursa without associated meniscal or ligamentous pathology. Due to persistent symptoms despite conservative management, arthroscopic excision was performed, confirming a ganglion cyst on gross pathology. The patient experienced complete resolution of symptoms without recurrence at the six-week follow-up. This case highlights the importance of considering pes anserine ganglion cysts in the differential diagnosis of chronic medial knee pain and underscores the critical role of MRI in accurate diagnosis and surgical planning.