Bulge Behind the Knee

No labs, no biopsies, no imaging -- only your seasoned clinical judgement is required to make a diagnosis in this case.

No labs, no biopsies . . .  you can make this Doorway Diagnosis just by looking.

Pictured is the posterior right knee of a 69-year-old woman showing a rounded protuberance at the popliteal fossa.


Based on what you see, what is your diagnosis?