OVERVIEW
Polyarteritis nodosa is a rare disease characterized by necrotizing vasculitis involving multiple systems and organs. It mainly involves small and medium-sized arteries, but may also involve capillaries and veins. It is most common in women aged 20 to 40 years. Some patients have ocular involvement, and almost any ocular tissue can be affected, such as the presence of conjunctival congestion, edema, subconjunctival hemorrhage, Sjögren’s syndrome, scleral episcleritis, scleritis, ulcerative keratitis, uveitis, neuro-ophthalmic damage, and orbital involvement.
Etiology
The etiopathogenesis is not fully understood. It has been suggested that some viruses such as hepatitis B virus, human immunodeficiency virus, cytomegalovirus, hepatitis A and C viruses, and microvirus spp. may play a role in the development of the disease, and that these viruses may promote leukocyte adherence by inducing the expression of Fc receptor and C3B receptor of vascular endothelial IgG and promoting the expression of MHC-II class II antigens in the endothelial cells and the production of IL-1, and other mechanisms. Involved in the development of the disease; it has also been suggested that autoimmune responses to endothelial cells may also play a role in its development; current studies also show that it is a T-cell mediated disease.
Symptoms
1. Ocular manifestations
Some patients have ocular involvement, and almost any ocular tissue can be affected, such as the development of conjunctival congestion, edema, subconjunctival hemorrhage, Sjögren’s syndrome, outer layer of sclera, scleritis, ulcerative keratitis, uveitis, neuro-ophthalmologic damage, and orbital involvement.
(1) Scleral episcleritis Scleral episcleritis and scleral keratitis: Inflammation of the superficial sclera, sclera, and corneal limbal blood vessels can cause scleral episcleritis, scleral episcleritis, and scleral keratitis; scleral episcleritis with peripheral corneal ulcers is a common ocular manifestation of the disease, and the patient often has severe ocular pain, with the peripheral corneal ulcers progressing to the center of the cornea, and in severe cases, the cornea may perforate, and the scleral episcleritis may act as the initial manifestation of polyarteritis nodosa. Scleral episcleritis can be the initial manifestation of polyarteritis nodosa, therefore, patients with scleral episcleritis should think of the possibility of this disease.
(2) Uveitis can be manifested as acute non-granulomatous iritis, vitritis, non-granulomatous total uveitis, choroidal vasculitis, retinal vasculitis and so on, which are all caused by vascular involvement of the uvea or retina.
2. Systemic manifestations
This disease can involve any tissue or organ, the most commonly involved are skin, kidney, cardiovascular, gastrointestinal tract, muscle, bone, nervous system and eyes, the systemic manifestations are usually non-specific, mainly fever, headache, weight loss, muscle pain, joint pain, testicular pain and so on.
(1) Skin lesions Half of the patients present with skin lesions, the most common of which are palpable purpura and subcutaneous nodules. Subcutaneous nodules are mostly distributed in clusters along superficial arteries, and these nodules are most common around the knee joints, the anterior lower limbs, and the insteps, which can be thrombotic and cause infarctions in tissues, and are especially prone to occur in the fingers and toes, which are manifested as palpable nodules, purpuric spots, or hemorrhagic maculopapularity.
(2) Renal damage Most patients have renal damage, mainly manifested as hypertension, proteinuria and hematuria, often accompanied by mild to moderate azotemia, renal infarction or rupture of intrarenal aneurysm can cause sudden onset of abdominal pain, which can be life-threatening in severe cases.
(3) Cardiovascular changes are common systemic manifestations, including hypertension, coronary artery thrombosis, pericarditis, intrapericardial hemorrhage, acute aortic arteritis, cardiac arrhythmia, and heart failure.
(4) Neurological changes Motor and sensory nerve disorders, polyneuritis, etc. may occur.
(5) Gastrointestinal changes The mesentery, intestinal mucosa, submucosal vasculitis, and infarction of the liver and spleen may cause abdominal pain, and intestinal gangrene, peritonitis, intestinal perforation, and intraperitoneal hemorrhage may also occur.
(6) Other systemic changes Non-invasive and non-deforming arthritis, muscle pain, epididymitis, etc. may occur.
Examination
1. Blood test
There may be the following abnormalities: (1) accelerated blood sedimentation; (2) neutrophilia; (3) increased serum globulin level; (4) positive hepatitis B antigen; (5) positive condensin; (6) circulating immune complexes; (7) positive anti-neutrophil cytoplasmic antibody.
2. Urine examination
Hematuria, erythrocyte tubular pattern, proteinuria, etc. may appear.
3. Histologic examination
Necrotizing segmental vasculitis is helpful for diagnosis. Histological changes mainly include destruction of the inner elastic membrane with deposition of fibrous material, infiltration of neutrophils and monocytes in the vessel wall, and granulomatous changes in the later stage. Fluorescence fundus angiography and indocyanine green angiography may reveal abnormal changes in the retinal and choroidal vessels.
Diagnosis
The diagnosis of this disease is mainly based on typical clinical manifestations and histologic examination.
Differential diagnosis
This disease should be distinguished from some diseases accompanied by systemic vasculitis, such as Behcet’s disease, systemic lupus erythematosus, mixed connective tissue disease, progressive systemic sclerosis, dermatomyositis, etc. The uveitis caused by this disease should be distinguished from non-granulomatous uveitis caused by other reasons, such as acute anterior uveitis associated with ankylosing spondylitis and acute anterior uveitis with positive HLA-B27 antigen, Behcet’s disease uveitis, sarcoidosis uveitis, idiopathic retinal vasculitis, tuberculous uveitis, and syphilitic uveitis.
Complications
Choroidal vasculitis and retinal vasculitis are the most common.
Treatment
Systemic involvement in this disease often requires treatment with immunosuppressive agents (e.g., glucocorticoids, cyclophosphamide, nitrogen mustard phenylbutyrate, azathioprine, cyclosporine, methotrexate, etc.). The most commonly chosen treatment regimen is cyclophosphamide in combination with glucocorticoids, which is generally prolonged and prone to toxic side effects, and therefore should be followed up regularly during treatment.
The treatment of ocular lesions, especially scleritis, keratitis and uveitis, is basically the same as that of systemic lesions, and concomitant glucocorticoid spot treatment should be considered for those with anterior segment involvement. In the presence of anterior uveitis, ciliary muscle paralyzer drops should also be given.
Prognosis
With aggressive and effective treatment, the 5-year survival rate has increased to 80% to 90%. Scleritis, uveitis, and ulcerative keratitis can result in severe or complete loss of vision.