18F-FDG PET/CT in polyarteritis nodosa with multisystem involvement: utility in defining disease extent.

Polyarteritis nodosa (PAN) is a rare systemic necrotizing vasculitis. It affects the medium-sized arteries. It attacks many parts of the body in very different ways. Therefore, it is difficult to diagnose and stage. 18F-fluorodeoxyglucose (18F-FDG) PET/CT combines anatomic and metabolic activity. This can show the complete extent of the disease in PAN very well. We report a 35-year-old man with fever, generalized myalgia, black stools and dry gangrene at the tip of his fingers. Laboratory tests revealed high C-reactive protein and high erythrocyte sedimentation rate. However, the anti-neutrophil cytoplasmic antibodies (ANCA) were negative. 18F-FDG PET/CT identifies multisystem lesions. The doctor thought that these lesions were there, but they could not be found by regular scanning. These lesions include high activity of many muscles, more absorption of the middle artery of the calf, local absorption of the skin between the toes, and absorption of the stomach wall. Tissue samples from many places confirmed necrotizing arteritis. After treatment with corticosteroids and targeted antibiotics, the patient's condition improved.