Pulmonary Infiltrate - A Detailed Analysis

Introduction:

A pulmonary infiltrate can be defined as an abnormal substance or type of cell that resides within the respiratory tract in a quantity greater than normal and foreign to the lungs. It creates a bridge between patients and severe respiratory disorders. Viruses or bacteria mostly form these infiltrates.

What Is Pulmonary Infiltration?

Pulmonary infiltration can be any substance that may cause damage to the lungs. The most common types of lung infiltrates are:

• Blood - Seen in tuberculosis.

• Pus - Seen in pneumonia.

• Water - Seen in pulmonary edema.

• Protein - Seen in a few pulmonary diseases.

• Inflammatory mediators.

• Neoplastic cells.

What Are the Causes of Pulmonary Infiltration?

The following can cause pulmonary infiltration:

Infections:

• Bacterial Pneumonia- is most commonly seen in patients with ventilation-associated pneumonia in intensive care units (ICU). A ventilator is a mechanical device that helps a person who is unable to breathe by themselves. It is mostly caused by aspiration of the oropharyngeal content. A simple tracheostomy or oropharyngeal intubation aids the passage of bacteria from the oropharynx to the respiratory airways. Formation of colonies by gram-negative bacteria occurs within twenty-four hours of ICU (intensive care unit) admission. The clinical presentation is non-specific. However, it may present with fever, worsening of hypoxemia, increased white blood count, increased respiratory rate and heart rate, and purulent tracheal secretion. Radiographically, new or progressive pulmonary infiltrates may be seen. A typical finding in the radiograph is the bilateral opacities and silhouette signs, but they are non-specific. However, signs, symptoms, and X-ray findings are inconclusive for the diagnosis. The sample collected from a bronchoscopy can provide a reliable diagnosis and differentiate the pathogenic load. The management depends upon broad-spectrum antibiotic coverage.

• Tuberculosis: It spreads by inhalation of aerosolized droplet nuclei from other infected patients. It is caused by mycobacterium tuberculosis, a part of a type of organisms, including M. Bovis and M. aricanum. Once inhaled the organism lodges in the alveoli and initiates the recruitment of macrophages and lymphocytes. These macrophages transform into epithelioid and Langhans cells, which aggregate to form a classical tuberculous granuloma. Several granulomas aggregate to form a primary lesion or Ghon focus which is characteristically present in the periphery of the lungs. A similar pathological reaction follows the spread of the microorganisms to the hilar lymph node. The combination of a primary lesion and regional lymph nodes results in the primary complex of Ranke.

Neoplastic:

• Primary Lung Cancer: It is one of the most common cancers worldwide. Cigarette smoking is the most common cause associated with it. The symptoms include cough dyspnea, hemoptysis, and pleuritic chest pain. The management involves surgical resection of the neoplasm, chemotherapy, and radiotherapy depending on the stage, resectability, and operability.

• Alveolar Cell Carcinoma.

• Lymphoma.

Non-Infectious and Non-Neoplastic:

• Radiation Pneumonitis: Pneumonitis caused by radiation is a form of lung injury. Pneumonia is an allergic reaction to an irritant, caused by bacteria or viruses. Certain individuals may develop radiation pneumonitis after undergoing radiation therapy specifically targeting the lungs or thoracic region. Although it typically manifests between 4 and 12 weeks following radiation therapy. On other occasions, the condition gradually manifests itself over several months.

• Lobe Torsion: It is a severe, life-threatening, rare in origin pulmonary condition characterized by rotation of the lung lobe around the bronchus and vascular supply. It can be secondary to a pathologic condition or idiopathic and spontaneous. The mainstay of treatment is surgical resection.

• Lung Contusion: It is usually associated with blunt trauma or penetrating injury to the chest. It is usually caused by disruption of the vessels of the alveolar walls and leakage of the blood into the alveolar spaces. On chest radiography, consolidations may be seen, which are usually faint and may improve with time. High mortality and morbidity are associated in patients with ventilator-associated pneumonia with pulmonary contusion.

• Lipoid Pneumonia: It is a rare condition, caused due to entry of fat particles into the airways. Lipidoids or lipoids, are molecules of fat, pneumonia is characterized by damage to the lining of the lung.

• Pulmonary Embolism: It is the formation of blood clots that may block the pulmonary vessels. The clot is usually formed in the deep veins of the legs and may travel toward the lungs. The typical clinical presentation is central cyanosis, increased jugular venous pressure, shortness of breath, chest pain, cough, fever, tachycardia, hypertension, and leg pain or swelling, usually in the calf muscle. The radiographic findings include prominent hilar vessels and oligemic lung fields. The management includes the administration of anticoagulants or blood thinners. Also, leg elevation and compression stockings may be useful in such cases. Even physical activity soon after surgery can help prevent pulmonary embolism.

What Are the Pulmonary Diseases in Which Pulmonary Infiltrates Can Be Seen?

Pulmonary infiltrates can occur in various diseases, such as:

• Tuberculosis

• Pneumonia.

• Silicosis.

• Asbestosis.

• Cystic fibrosis.

• Actinomycosis.

• Sarcoidosis.

• Scleroderma.

• Pulmonary edema.

• Pulmonary tumors.

• Allergic alveolitis.

• Amyloidosis.

• Pulmonary parasitosis.

• Leukemias.

What Is Pulmonary Consolidation?

The areas of the lungs where the alveolar spaces are filled with atypical substances instead of air are known as pulmonary consolidations. It is a solidification of the lung tissue due to the accumulation of solid and liquid material in the alveolar spaces that would have been filled normally by air. It is usually characterized by a marked swelling of the lung tissue, thereby obstructing the airways in the affected portions of the lungs. It can occur in various diseases such as pulmonary malignancies, infarction, and pneumonia and produces significant radiographic signs. The typical symptoms include:

• Noisy breathing.

• Difficulty in breathing or shortness of breath.

• Coughing up blood or hemoptysis.

• Chest pain.

• Rapid breathing or tachypnea.

• Fever.

• Fatigue.

The most common causes of lung consolidation are:

• Pneumonia is the most common cause of pulmonary consolidation. Although bacteria or viruses usually cause it, it can sometimes be caused by fungi too. Dead cells and debris accumulate, producing purulent substances that fill up the small airways.

• Pulmonary edema is seen in congestive heart failure, where the heart cannot pump blood forward. Therefore, all the blood regurgitates back into the pulmonary vessels, making breathing difficult.

• Pulmonary hemorrhage.

• Aspiration of food particles into the lungs.

• Lung cancer.

What Are the Pulmonary Complications in Immunocompromised Individuals?

People who are immunocompromised who are having HIV or are at risk of getting HIV often have pulmonary infiltrates, which are often followed by fever, shortness of breath, and cough.

Respiratory Complications

Immunocompromised patients such as AIDS, would develop respiratory problems that can show up in ways that are not usual. The respiratory complications include the following:

• Tuberculosis- Tuberculosis (TB) is an airborne and transmissible illness that destroys tissue. In pulmonary tuberculosis, which attacks only the lungs and can spread to other organs, it can be cured with early identification and antibiotic therapy. Pulmonary tuberculosis in people with advanced HIV infection may not show up on X-rays or may show up in a way that is not usual.

• Pneumocystis Pneumonia- A severe illness, pneumocystis pneumonia (PCP) is characterized by fluid accumulation and inflammation of the airways. The pathogen responsible for its transmission is Pneumocystis jirovecii, a fungus common in the atmosphere.

When individuals initially present with diffuse lung infiltrates, they are frequently diagnosed with Pneumocystis pneumonia due to their compromised CD4 count and inadequate protection, which places them at a heightened risk.

• Kaposi Sarcoma- Kaposi sarcoma is cancer cells that can be found in the skin or the mucous membranes that line the GI system, which is made up of the stomach, intestines, and the area from the mouth to the anus. The person is likely detected with Kaposi sarcoma if they have typical lesions in their lungs.

Conclusion:

Pulmonary infiltrates are abnormal substances that build up in the alveolar spaces. They can be blood, pus, interstitial fluid, protein, inflammatory mediators, neoplastic cells, and more. The infiltrates can be appreciated on a chest radiograph, and the treatment involves resolving the underlying cause. Once the etiology is removed, the condition subsides on its own.