Musculoskeletal disorders 

Large vessel vasculitis includes giant cell arteritis (over 50, headache, jaw claudication, visual loss) and Takayasu arteritis (young women, absent pulses); medium vessel vasculitis includes polyarteritis nodosa and Kawasaki disease in children under 5. Treat with high-dose steroids plus methotrexate, tocilizumab, azathioprine or cyclophosphamide, and Kawasaki disease with IVIG and aspirin.

Small vessel vasculitis includes GPA, MPA and EGPA (ANCA-associated), IgA vasculitis (Henoch–Schönlein purpura), cryoglobulinaemic vasculitis, anti-GBM disease and urticarial vasculitis, affecting the skin, lungs and kidneys. Treatment is prednisolone with cyclophosphamide or rituximab, adding pulse methylprednisolone and plasma exchange for life-threatening disease.

Joint hypermobility syndromes (JHS, Ehlers-Danlos types, Marfan syndrome, osteogenesis imperfecta) cause excessive joint range, pain, instability, dislocations and, in some types, arterial, eye or bone fragility; the Beighton score assesses hypermobility. Management is physiotherapy, education and occupational therapy with NSAIDs, baclofen and joint supplements for symptoms.

Antiphospholipid syndrome is persistent antiphospholipid antibodies with venous or arterial thrombosis or pregnancy loss, alone or with SLE. Give low-dose aspirin for primary prevention, lifelong warfarin (INR 2–3) after thrombosis, and aspirin plus LMWH throughout pregnancy and postpartum.

Fibromyalgia is chronic widespread pain for 3 months or more with fatigue, poor sleep and cognitive problems from central pain sensitisation, diagnosed with the 2016 ACR criteria after excluding other causes. Management starts with education, graded exercise, CBT and sleep hygiene, adding duloxetine or amitriptyline for persistent symptoms.