E1174. Beyond the Baker's Cyst: Variant Anatomy and Pathology of the Popliteal Fossa
  1. Adam Baker; Icahn School of Medicine at Mount Sinai
  2. Etan Dayan; Icahn School of Medicine at Mount Sinai
  3. Clara Yoo; Icahn School of Medicine at Mount Sinai
In this educational exhibit, we will demonstrate a wide range of variant anatomy within the popliteal fossa, a natural blind spot in the diagnostic search pattern for radiologists. Radiologic references for the popliteal fossa are lacking, and the authors felt a succinct review could be beneficial for radiologists in training and practice alike. We have compiled an educational exhibit and presentation that emphasizes the breadth of important anatomic variations and pathology found in this space - beyond the Baker's cyst!

Educational Goals / Teaching Points
The popliteal fossa is a natural blind spot on routine knee MRI, a common study generally obtained for knee pain. Primary evaluation focuses on evaluation of cartilaginous degeneration, meniscal injury, ligamentous or tendinous abnormality, and bone marrow lesions, rather than the popliteal fossa. A comprehensive knowledge of normal popliteal fossa anatomy and fat planes is key to recognizing clinically significant pathology and variant anatomy.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Abnormal insertion of the medial head of the gastrocnemius, or an accessory head of the gastrocnemius, can increase the risk of popliteal artery entrapment, an under recognized cause of posterior calf and knee pain. Abnormal branching and course of the popliteal artery can increase risk of surgical vulnerability during multiple knee procedures, including arthroscopy and high tibial osteotomy. Finally, not all masses in the popliteal fossa are Baker’s cysts; synovial sarcomas, vascular malformations, and other tumors can present in this anatomic space and can mimic popliteal cysts. Each of these will be presented in an MRI based case series drawn from home institution cases.

Through this educational exhibit, radiologists will gain a better understanding of normal anatomy of the popliteal fossa, and the importance of including this region into their core diagnostic search pattern. Various pathology presented will expand their differential for knee and calf pain. Radiologists will ascertain the clinical importance of variant anatomy within the popliteal fossa and how it may impact surgical management of the patient.