What are the key clinical features that suggest a diagnosis of Polyarteritis Nodosa in a patient presenting with systemic symptoms?

Key clinical features suggesting a diagnosis of Polyarteritis Nodosa (PAN) in a patient with systemic symptoms include:

• Constitutional symptoms: Persistent fever, weight loss, and malaise are common initial presentations reflecting systemic inflammation ¹ (Pettigrew et al., 2025).
• Musculoskeletal symptoms: Myalgia and arthralgia, often involving multiple joints, are frequent and may precede other organ involvement ¹ (Hočevar et al., 2021).
• Skin manifestations: Livedo reticularis, tender subcutaneous nodules, and ulcerations due to medium-sized artery involvement are characteristic ¹ (Hansen et al., 2022).
• Neurological signs: Mononeuritis multiplex or peripheral neuropathy presenting as asymmetric sensory and motor deficits is a hallmark feature ¹ (Hočevar et al., 2021).
• Renal involvement: Hypertension and renal impairment without glomerulonephritis, reflecting medium-vessel vasculitis, are typical ¹ (Pettigrew et al., 2025).
• Gastrointestinal symptoms: Abdominal pain, often postprandial, nausea, and possible mesenteric ischemia due to vasculitis of mesenteric arteries ¹ (Hansen et al., 2022).
• Absence of ANCA antibodies: Unlike other vasculitides, PAN is typically ANCA-negative, which helps differentiate it clinically ¹ (Hočevar et al., 2021).

These features together, especially systemic symptoms combined with medium-sized artery involvement manifesting as skin, neurological, renal, and gastrointestinal signs, strongly suggest PAN. Diagnosis is supported by clinical suspicion and confirmed by angiography or biopsy demonstrating necrotizing vasculitis of medium-sized arteries ¹ (Pettigrew et al., 2025; Hočevar et al., 2021).