9th June 2025

A 50-year-old male patient presents with fever, arthralgia and skin lesions that have persisted for more than 24 hours and have left a dark bruise.

A 50-year-old male patient presents with fever, arthralgia and skin lesions that have persisted for more than 24 hours and have left a dark bruise. He has also noted mild ankle oedema over the last 2 days. Urine dip is positive for protein and blood. Blood tests show: 

Hb 123 g/L Male: (135-180)

Platelets 500 * 109/L (150 – 400)

WBC 10.0 * 109/L (4.0 – 11.0)

Na+ 142 mmol/L (135 – 145)

K+ 4.3 mmol/L (3.5 – 5.0)

Urea 14 mmol/L (2.0 – 7.0)

Creatinine 147 µmol/L (55 – 120)

CRP  89 mg/L   (< 5)

Which of the following is the most likely diagnosis?