Fever and arthritis in a 64-year-old man

A 64-year-old man presented with high fever (38–39°C oral temperature), severe joint pains with explosive onset, and substantial weight loss (4 kg in 1 month). On examination, he had dorsal oedema on the hands (figure) and symmetrically tender and swollen joints (ie, proximal interphalangeal joints, metacarpophalangeal joints, wrists, elbows, and knees). Additionally, he had generalised lymphadenopathy (bilateral upper cervical, left lower...