MSFinals-4466

A 16-year-old girl visits her GP complaining of bilateral knee pain that has been bothering her for the past 2 months, particularly in the mornings. She has also been feeling generally fatigued, but denies experiencing any fevers, weight loss, or rashes. Her mother has a history of systemic lupus erythematosus (SLE), but otherwise, her family history is unremarkable. Upon examination, the patient’s vital signs are within normal limits. There is mild oedema in both knees and ankles, and passive movement of the knee joints elicits tenderness. What is the most likely diagnosis?