Uncommon Radiological Manifestations of Pulmonary Vasculitis

Introduction

Vasculitis is a broad term used for diseases that affect the blood vessels of the body. Inflammation of the blood vessels is the characteristic hallmark of this disease. The blood vessels - arteries, veins, or capillaries - allow for a smooth flow of blood throughout the body. In a diseased patient, the inflamed vessels constrict the vessel diameter. This, in turn, interrupts the flow of blood in the affected region. The human body comprises an intricate network of varying sizes of blood vessels that supply blood to all the organ systems of the body. Vasculitis can affect large, small, or both categories of blood vessels. The severity of vasculitis often depends on the stage of the disease, the organ system it acts on, and the health status of the patient. This article aims to discuss how vasculitis impacts the lungs and the varied radiological findings obtained in patients suffering from pulmonary vasculitis.

What Is Pulmonary Vasculitis?

Vasculitis shows clinical manifestations in several organ systems of the body. Lungs are one of the most commonly affected organs owing to the rich vasculature they exhibit. Pulmonary vasculitis comprises a wide range of clinical features and radiological manifestations that are observed to overlap in the majority of patients. Classification of pulmonary vasculitis is a tough task to achieve. However, based on radiological findings, this disease is categorized into three groups:

1. Angiitis-granulomatosis group: this typically shows localized nodular and patchy opacities

2. Diffuse pulmonary hemorrhage due to capillaritis: particularly reveals diffuse air space consolidation

3. Aneurysm or stenosis of the large pulmonary arteries: as observed in Takayasu arteritis and Behcet’s Disease.

A detailed discussion of specific characteristics demonstrated by each of these groups will be the main focus of the rest of the article.

What Are the Radiological Characteristics of Pulmonary Vasculitis?

Considering one group at a time, the following are the radiographic manifestations of pulmonary vasculitis.

1. Angiitis-Granulomatosis Group: This group includes several conditions that show a generalized picture of the presence of multiple nodules that may or may not be accompanied by cavities or pleural-based consolidation that closely resembles a pulmonary infarct. These conditions include:

• Wegener’s Granulomatosis: This condition affects the lungs and airways but may also involve other body parts like the nose, eyes, ears, and kidneys. It is generally found to occur at 50 years of age, and 90 percent of cases show critical lung involvement. The radiographic assessment depicts bilateral, rounded opacities ranging from a few millimeters to about 3.94 inches. In cases presenting with small vessel vasculitis, bilateral airspace consolidation due to pulmonary hemorrhage is quite significant. The CT (computed tomography) provides a clearer picture by showing masses or thickening of the tracheobronchial tree and, in some cases, also reveals lung collapse. Other uncommon findings include interstitial disease, pneumothorax, and bronchopleural fistula.

• Allergic Angiitis and Granulomatosis: This condition is typically marked by an increase in the eosinophil level and is often seen in addition to asthma. Middle age is when it is most frequently reported in patients. The radiological manifestation generally observed is non-segmental air space consolidation, just as seen in eosinophilic pneumonia. Cavitation of nodules is quite rare, unlike Wegener’s granulomatosis. It is a multiorgan system disorder and may show clinical manifestations in the skin, nervous system, gastrointestinal tract, heart, kidney, and joints as well.

• Necrotizing Sarcoid Granulomatosis: Characterized by signs of necrosis and vasculitis, this disease is more prominent in women, and the age of onset is not very specific. Radiographically, multiple bilateral nodules are observed. However, a characteristic solitary nodule is also found in about 25 percent of patients.

• Lymphomatoid Granulomatosis: The radiological findings of this condition include multiple masses with an ill-defined margin. The upper respiratory tract is not commonly involved.

• Bronchocentric Granulomatosis: This disease is different from other granulomatosis diseases discussed above, as it typically involves the airways rather than the blood vasculature. The radiographic depiction of this disease includes a large opacity ranging from 0.79 inches to 2.36 inches in diameter, in addition to multiple nodules, areas of consolidation, and, in some cases, cavitation. They are generally unilateral and predominantly affect the upper airway.

2. Diffuse Pulmonary Hemorrhage (DPH) Due to Capillaritis: This particular group is marked by rupture of tiny vasculature present in the lungs, which ultimately leads to hemorrhage into the alveolar spaces. In its acute stage, DPH is characterized by diffuse air space consolidation, generally involved bilaterally. The lung periphery is rarely affected. The acute phase is followed by blood absorption into the interstitial spaces, displaying a reticular pattern. Upon repeatedly encountering such episodes, the reticular pattern develops further, and fibrosis of the interstitial spaces is observed. The CT scan reveals ground-glass opacity in the acute stage. The conditions that show DPH include:

• Microscopic polyarteritis nodosa.

• Systemic lupus erythematosus.

• Goodpasture’s syndrome.

• Mixed cryoglobulinemia.

• Henoch-Schonlein purpura.

3. Aneurysm or Stenosis of Large Pulmonary Arteries: The two diseases that show massive involvement of the large pulmonary arteries include:

• Takayasu Arteritis: This disease typically affects the thoracic, major branches of the abdominal aorta, and the pulmonary artery. Stenosis is observed as a common angiographic finding. The CT scan reveals a thickening of the vessel wall.

• Behcet’s Disease: This disease is a chronic condition and involves multiple organs. The thoracic involvement includes aneurysm of the pulmonary artery and shows signs of pulmonary infarction and hemorrhage. Thrombosis of the superior vena cava is also observed. The radiographic assessment shows marked mediastinal widening, opaque lung mass owing to the aneurysm of the artery, or air space consolidation formed as a result of infarction or hemorrhage.

Conclusion

To summarize this article, pulmonary vasculitis is characterized by inflammation of blood vessels that are located in the lungs that may show signs of aneurysm, hemorrhage, or infarction. The classification of pulmonary vasculitis described here is solely based on the radiological findings of the disease and differs greatly from the conventional clinical classification of the disease. However, the radiographic findings make up the base for diagnosing the condition in suspected pulmonary vasculitis patients and, hence, aid the radiologist in checking out the several differential diagnoses associated with it.