Introduction and Importance:
Hoffa’s fat pad, also known as infra-patellar fat pad, is one of the three fat pads in the knee. Ganglion cyst rarely arises from Hoffa’s fat pad which presents with knee pain and swelling.
Case Presentation:
A 43-year-old female presented with left knee pain for one year and swelling in left knee for six months. Clinical examination revealed a palpable swelling of size around 3 cm x 2 cm over the anteromedial aspect of the left knee. The size of swelling increased on extension and decreased on flexion of knee. Musculoskeletal ultrasound of the left knee revealed a lobulated anechoic lesion of size ~2.3 x 2 cm in Hoffa’s fat pad. Open excision of cystic mass through medial parapatellar approach was done and histopathological examination showed findings consistent with ganglion cyst. At six months follow up, there was no residual swelling and no recurrence. She was symptom- free on her recent evaluation after one year of operation.
Clinical discussion:
Ganglion cyst arising from Hoffa’s fat pad is much rarer among the cyst around the knee. Diagnosis is primarily done by magnetic resonance imaging. However, use of ultrasonography has grown in diagnosis of the ganglion cyst. Among different modalities of treatment, open excision is the most recommended to prevent recurrence and incomplete resection.
Conclusions:
This case illustrates the importance of ultrasonography in early diagnosis of Hoffa’s fat pad ganglion cyst and reserving more costly and time-consuming imaging modality magnetic resonance imaging for localizing the extent of the cyst. We recommend an open resection to avoid recurrence and incomplete resection of the cyst.