Polyarteritis nodosa (PAN) is a rare autoimmune disease that affects medium-sized arteries and causes inflammation and damage to the blood vessel walls. Testicular pain is an uncommon symptom of PAN but can occur in rare cases. This specific symptom may be useful in diagnosing older patients with limited tissue access because of their vulnerability and high risk for biopsy complications. We report the case of a 78-year-old male patient with progressive fatigue and walking difficulty. After ruling out various forms of vasculitis and malignancy, we diagnosed the patient with PAN and intensively treated him with rituximab, which successfully cured his symptoms. This case report highlights the importance of intensively ruling out possible diagnoses mimicking vasculitis and treating vasculitis with a tentative diagnosis of PAN in older patients in rural hospitals. The progressive clinical course of vasculitis may devastate older patients' activities of daily living (ADLs). PAN may particularly affect older patients with possible hepatitis B infections. Thus, shared decision-making and prompt intensive treatment should be considered.