MRCP2-4701

A 32-year-old teacher presented with a three week history of ankle pain, swelling, and stiffness. He also reported a cough and mild shortness of breath during physical activity. Upon examination, his ankles were warm, tender, and swollen. His chest appeared normal. Blood tests for FBC, U&E, and LFTs were all normal. Rheumatoid factor and anti-CCP antibodies were negative. However, his CRP was high at 38 mg/L, and his serum ACE was 133 units (normal range is 0-65 units). A chest X-ray revealed bilateral hilar lymphadenopathy and reticulonodular shadows in the lung fields. What is the most likely diagnosis?