Diagnosis

Prompt

A female patient of 25 years of age complains of elbow pain since one year. On examination, there is a deficit of 15 degrees of extension and 15 degrees of flexion. There is swelling at anconeus triangle and tenderness. Her blood examination shows CRP 2 eSR 27. Rheumatoid factor and anti-CCP are both negative. X-rays do not show any osteophytes. MRI shows grade 2 to 3 synovites, moderate effusion, internal septations, irregular synovial thickening, no marrow edema, no blooming artifact. Tendons and ligaments are normal. The joint is congruent. What could be the diagnosis?