Granulomatosis With Polyangiitis Thoracic Imaging- An Overview

What Is Granulomatosis With Polyangiitis?

Granulomatosis with polyangiitis (GPA), formerly known as Wegener’s granulomatosis, is an uncommon disorder affecting small to medium-sized blood vessels that supply the upper respiratory tract (nose, sinus, windpipe), lungs, and kidneys. This disorder is characterized by inflammatory mass around the dead blood vessels (necrotizing granuloma) and progressively restricts the blood flow to the respective organs.

What Is the Cause of Granulomatosis With Polyangiitis?

The underlying cause of GPA is not certain to date. In most cases, the cause of GPA is linked to antineutrophilic cytoplasmic antibodies (ANCA). Neutrophils are a type of white blood cells that balance inflammation and heal dead tissues in the body. ANCA are directed against neutrophils and disrupt their normal function. In such cases, inflammation is not resolved, and neutrophils release chemicals that, in turn, damage the lining of the blood vessels. GPA is common in middle-aged adults and rare in children.

What Are the Signs and Symptoms of Granulomatosis With Polyangiitis?

• Fever, weight loss, muscle pain (myalgia), multiple joint pain (polyarthralgia).

• GPA usually starts with sinus pain, nasal pain, pus charge, and bleeding from the nose and middle ear infection.

• The condition deforms the bridge of the nose by perforating the nasal septum, which separates the two nasal openings (saddle nose deformity).

• It is progressed by cough, chest pain, difficulty in breathing, coughing up blood, and obstruction of the windpipe resulting in harsh sound while breathing (stridor).

• This disorder affects kidneys rarely but being negligent can involve kidneys within two years of the disease onset. It affects the tiny filtering structures called glomeruli that filter blood in the kidneys and result in kidney failure.

• Bulging of eyeballs, double vision, or vision loss.

• Heart involvement is also seen.

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• Multiple joint pain, muscular pain, and nerve pain are reported.

How to Diagnose Granulomatosis With Polyangiitis?

• Blood Tests: Patients suspected of having GPA are advised to do the following blood tests.

• Check for the presence of antineutrophil cytoplasmic antibodies (ANCA).

• Check for a high C- reactive protein/high erythrocyte sedimentation rate.

• Kidney function test.

• Hemoglobin test to detect anemia.

• Urine Test: Urine samples of suspected individuals should be collected and checked for the presence of high protein and red blood cells.

• Biopsy: Examining lung and kidney tissues under slides (histological examination) can give a definitive diagnosis of GPA. The affected tissue shows necrotizing granuloma (inflamed non-cancerous tissue) that appears with central necrosis and surrounding histiocytes and giant cells.

• Radiology: Computed tomography(CT) and magnetic resonance imaging (MRI) serve to diagnose GPA.

• Computed Tomography Findings in Granulomatosis With Polyangiitis: Pulmonary nodules that can be solid/ground glass opacified/cavitary nodules are seen. Bronchial wall thickening, lung wall (pleura) thickening, pulmonary artery (blood vessel from heart to lungs) wall thickening.

• MRI Findings in Granulomatosis With Polyangiitis: MRI has advantages over CT in detecting blood flow and malformations in a blood vessel. MRI does not produce ionizing radiation (that induces cancer cell formation) and is thus safer than other radiological examinations. T1 weighted images-shows low to intermediate signal intensity nodules/ Mass mucosal lesions. T1 C+ (Gad) - shows enhanced involved mucosal tissue. T2 -shows a low signal intensity nodule compared to the surrounding edematous (inflamed) tissue.T1-weighted images enhance signals from fatty tissue, and T2-weighted images enhance signals from water (fluid). T1 Gad refers to the usage of gadolinium, which is a contrast-enhancing agent and is used in detecting tumors, inflamed cells, etc.

What Are the Diagnostic Criteria for GPA?

Diagnostic criteria are given by The American College of Rheumatology (1990) for the diagnosis of GPA to distinguish the disease from other vasculitis:

• Urinary sediment containing red cell casts/ Microhematuria (> 5 red blood cells per high-power field).

• Abnormal findings on the chest radiograph.

• Bloody nasal discharge or oral ulcers.

• Granulomatous inflammation on biopsy.

The presence of two or more of the criteria mentioned above confirms the diagnosis of GPA.

What Are the Life-Threatening Complications of GPA?

• Active glomerulonephritis.

• Pulmonary hemorrhage.

• Cerebral vasculitis.

• Progressive peripheral or cranial neuropathy.

• Gut bleeding.

• Inflammation of the heart wall (pericarditis).

• Inflammation of the heart muscle (myocarditis).

• Eye lesions mimicking eye cancer.

How to Treat and Manage Granulomatosis With Polyangiitis?

Individuals with severe GPA are treated under two phases:

• Induction phase.

• Maintenance phase.

1) Cyclophosphamide, combined with glucocorticoids, is used in the induction phase. In addition, intravenous administration of Prednisolone (pulse steroid) is frequently given before oral intake of glucocorticosteroid. Rituximab, glucocorticoids, Azathioprine, and Methotrexate are other drugs used to treat GPA. Clinical trials have proved Rituximab is effective in preventing relapses compared to Cyclophosphamide. In moderate cases, Methotrexate in combination with glucocorticoids can be used.

2) The maintenance phase is started when the signs and symptoms disappear (usually after three to six months of the induction phase). Rituximab, Azathioprine, and Methotrexate are used in the maintenance phase.

What Is Plasmapheresis?

This is indicated in GPA patients with compromised kidney functions, lung bleeding, and those who do not respond to intravenous corticosteroids. It is a process where blood is drawn through a needle or catheter and run through a machine that separates red blood cells, white blood cells, platelets, and plasma from the blood; then, the plasma is replaced with a protein fluid and sent into the body along with other components of blood.

What Are the Side Effects of the Drugs Used in the Treatment of GPA?

The drugs used in the treatment of GPA have potential side effects. The immunosuppressant activity of the drugs like Cyclophosphamide, Methotrexate, and Rituximab can decrease blood cell formation. If the patient is monitored periodically with blood tests, the condition would be discovered priorly, and drug dosage can be altered or stopped based on the severity. Rituximab can potentially cause sterility in younger individuals and urinary bladder cancer. Cyclophosphamide has the side effect of developing brain infection.

Conclusion

Granulomatosis with polyangiitis is a fatal disease producing irreversible damage to the internal organs. Proper follow-up with the concerned specialist can improve the quality of life in patients with GPA. The chest CT (computed tomography) findings in GPA concur with other lung diseases like pneumonia and other conditions. Clinical examination, laboratory test, and biopsy combined with CT and MRI (magnetic resonance imaging) to arrive at a definite diagnosis.