Polyarteritis Nodosa With Mesenteric, Hepatic, and Musculoskeletal Manifestations in a 36-Year-Old Nigerian Male Patient: A Case Report.

Polyarteritis nodosa (PAN) is a rare systemic necrotizing vasculitis affecting medium and small arteries, with heterogeneous clinical manifestations ranging from constitutional symptoms to life-threatening organ ischemia. We present the case of a 36-year-old male patient with PAN manifesting as severe abdominal pain and bilateral upper limb ischemia, highlighting the diagnostic and therapeutic challenges of this condition. Initial evaluation revealed elevated inflammatory markers and characteristic arterial stenosis with aneurysmal dilation on Doppler ultrasound, supporting a PAN diagnosis with negative antineutrophil cytoplasmic antibody (ANCA) serology. Treatment with high-dose glucocorticoids induced remission, underscoring the efficacy of immunosuppression in managing this disease. This case illustrates the importance of considering PAN in patients with unexplained ischemic symptoms, particularly in the absence of ANCA positivity. While glucocorticoids remain first-line therapy, emerging evidence supports the use of biologic agents in refractory cases. The discussion explores the evolving treatment paradigms, including the role of cyclophosphamide, tumor necrosis factor (TNF) inhibitors, and rituximab, while emphasizing the need for risk-stratified management. Given PAN's variable presentation and potential for severe complications, early recognition and tailored immunosuppressive therapy are crucial for optimizing outcomes.