Polyarteritis nodosa with abdominal pain as the main symptoms: A case report.

rationalePolyarteritis nodosa (PAN) is an uncommon systemic necrotizing vasculitis that is often misdiagnosed due to its rarity. Early diagnosis of PAN is critical, as prompt initiation of pharmacotherapy significantly improves the 5-year survival rate. However, a review of recent case reports indexed in PubMed reveals that the majority describe delayed PAN diagnosis, frequently associated with severe adverse outcomes, including fatalities. This pattern underscores the persistent diagnostic challenges in imaging for PAN. Thus, this case report contributes valuable insights to advance our understanding and recognition of PAN diagnosis. PATIENT CONCERNS: A 65-year-old female patient presented with abdominal pain without obvious cause. Laboratory investigations revealed hypoalbuminemia, elevated D-dimer and fibrin degradation products, decreased IgG, IgM, and C3 levels, and a positive antinuclear antibody at a titer of 1:100 with a coarse speckled pattern. Nerve conduction electromyography and abdominal computer tomography angiography were performed. Based on the collective findings, PAN was ultimately diagnosed. DIAGNOSES: Based on the findings of weight loss ≥ 4 kg, leg tenderness, polyneuropathy, and abnormal arteriography, the patient was ultimately diagnosed with PAN. INTERVENTIONS AND OUTCOMES: The patient received pulse methylprednisolone (500 mg/d × 3 days) and cyclophosphamide (400 mg q2w), followed by prednisone taper. Remission maintenance used prednisone 10 mg/d and methotrexate 7.5 mg/wk. After achieving remission, the patient maintained glucocorticoids and non-glucocorticoids for 2 years as consolidation therapy. Subsequently, all immunosuppressive agents were self-discontinued. At the telephone follow-up conducted 2 years after treatment cessation, the patient reported being asymptomatic and demonstrated no signs or symptoms related to PAN. LESSONS: This case highlights the diagnostic challenges and complexities of maintaining long-term remission in PAN patients. Thus, it is crucial for gastroenterologists to maintain a high index of suspicion and include PAN in their differential diagnosis when evaluating patients.