Polyarteritis nodosa

Disease Description (Causes and Symptoms)

• Definition summary: Vasculitis in which ischemia and damage to organs occur due to weakening and narrowing of the arterial walls and formation of microaneurysms caused by full-thickness inflammation of medium-sized arteries (the lungs are generally not involved).
• Causes and pathophysiology: Most cases are caused by autoimmune mechanisms (invasion of blood vessels by leukocytes and immune cells), although an association with hepatitis B and C has been reported in some patients. Inflammation causes full-thickness (transmural) vascular damage and fibrinoid necrosis, while microaneurysms, stenosis, and reduced blood flow in the vessels cause tissue ischemia.
• Main symptoms: Typically, symptoms involving the affected organs develop after several weeks to months of nonspecific systemic symptoms (fever, fatigue, weight loss, myalgia, and arthralgia).
  • Skin: Purpura (palpable purpura), ulcers, necrosis
  • Nervous system: Peripheral neuropathy (mononeuropathy or polyneuropathy, sensory and motor weakness), and rarely central nervous system symptoms
  • Kidneys: Hypertension and impaired kidney function due to renal artery involvement (unlike glomerulopathy, the lesions primarily affect the renal arteries)
  • Gastrointestinal tract: Abdominal pain (mainly around the navel), vomiting, diarrhea, and risk of intestinal bleeding and perforation
  • Cardiovascular system: Heart failure and myocardial injury may occur when the coronary arteries or myocardium are involved
• Characteristic findings: Multiple microaneurysms of the renal and abdominal vessels (“small multiple aneurysms”) may be observed on angiography. ANCA is generally negative.

Treatment

• General principles: Immunosuppressive treatment is initiated according to disease activity and the severity of organ involvement. The presence of infection, particularly hepatitis B or C, must be confirmed, and antiviral treatment should be given concurrently when viral hepatitis is suspected to be the cause.
• Drug treatment
  • Initial treatment (moderate or greater disease activity): High-dose oral or intravenous corticosteroids (e.g., prednisone).
  • Severe or life-threatening organ involvement: Induction therapy in combination with cyclophosphamide.
  • Maintenance therapy: Long-term maintenance with azathioprine, methotrexate, or other medications (according to the physician’s judgment).
  • Virus-related (PAN associated with HBV): Consider antiviral agents (e.g., anti-HBV medications) and, in some cases, plasmapheresis.
• Procedures/surgery: Surgical treatment may be necessary for complications caused by localized organ ischemia (e.g., intestinal perforation or myocardial ischemia).
• Lifestyle management and precautions
  • Infection prevention: Before immunosuppressive treatment, receive vaccinations when possible and minimize exposure to infections; seek medical attention promptly in case of fever or cold symptoms.
  • Blood pressure management: Strict blood pressure control is required when the kidneys are involved.
  • Long-term treatment: Regular follow-up and testing are necessary because relapse is possible.
  • Fertility preservation: When using cyclophosphamide, discuss its effects on fertility (risk of infertility) and, if necessary, seek counseling about cryopreservation.

Checkpoints Before an Outpatient Visit (Including Preparation Items and Example Questions)

• List of items to prepare
  • A list of all medications currently being taken (including prescription drugs, OTC drugs, herbal medicines, and supplements) or the medication packages
  • Records of past medical conditions, surgeries, and vaccinations (especially whether hepatitis B vaccination was received)
  • Recent test results (blood tests, urine tests, imaging tests, etc.); bring the actual test reports if available
  • A record of symptom changes (fever, weight changes, location and severity of pain, changes in urination or bowel movements, etc.), along with notes on blood pressure, body temperature, and when symptoms occurred
  • Family history (autoimmune diseases, hepatitis, etc.)
• Items to show the doctor during the outpatient visit
  • Recent test results (especially hepatitis tests, blood tests, and kidney function)
  • Detailed records of when symptoms began and how they have progressed, as well as factors that worsen or improve them
• Example questions (for an outpatient visit)
  • "Based on my current symptoms and test results, how active is the disease assessed to be?"
  • "What measures should I take to prevent infection during immunosuppressive treatment?"

General Example Questions to Ask the Doctor

• What are the major side effects of these medications (corticosteroids, cyclophosphamide, etc.), and how can they be prevented and monitored?
• How long does treatment usually last, and how high is the risk of relapse if the medication is stopped?
• Which vaccinations should I receive in advance during immunosuppressive treatment?
• What recommendations are there regarding pregnancy planning or fertility preservation?

Disease-Specific Example Questions

• Have I been tested to determine whether my disease is associated with hepatitis B or C? (What are the plans for future testing and treatment?)
• Are imaging studies (angiography) or biopsies (skin, nerve, or kidney biopsy) necessary? How would treatment change depending on the results?
• If I need to use potent immunosuppressants such as cyclophosphamide, should I receive counseling about fertility preservation (sperm or egg storage)?

(Note: Diagnosis and treatment may vary depending on the individual’s condition. The items above are intended as guidance for discussing these matters in detail with a doctor during an outpatient consultation.)