Pneumonitis

Pneumonitis
Synonyms	Pulmonitis
Pronounce	/ˌnjuːməˈnaɪtɪs/
Field	Pulmonology
Symptoms	Cough, dyspnea (shortness of breath), fatigue, chest discomfort, fever
Complications	Pulmonary fibrosis, respiratory failure, chronic lung disease
Onset	Acute or chronic, depending on cause
Duration	Variable (days to months); chronic cases may persist
Types	Hypersensitivity pneumonitis, Radiation pneumonitis, Chemical pneumonitis, Aspiration pneumonitis, Cryptogenic organizing pneumonia
Causes	Inhalation of allergens, chemicals, radiation, drugs, infections, autoimmune reactions
Risks	Occupational exposures, radiation therapy, immunosuppressive medications, aspiration risk
Diagnosis	Chest X-ray, CT scan, pulmonary function test, bronchoscopy, lung biopsy
Differential diagnosis	Pneumonia, asthma, chronic obstructive pulmonary disease (COPD), interstitial lung disease
Prevention	Avoid known triggers, use of protective respiratory equipment, prophylactic medications in specific cases
Treatment	Removal of cause, corticosteroids, oxygen therapy, immunosuppressive therapy in chronic cases
Medication	Prednisone, methylprednisolone, immunosuppressants, bronchodilators
Prognosis	Good if treated early; chronic forms may lead to irreversible lung damage
Frequency	Relatively rare; varies by type and geographic/occupational exposure
Deaths	Rare with prompt treatment; mortality higher in untreated or chronic severe cases

Hypersensitivity pneumonitis

Radiation pneumonitis

Pneumonitis is an inflammation of lung tissue due to factors other than microorganisms. Those can be radiation therapy of the chest, exposure to medications used during chemo-therapy, the inhalation of debris (e.g., animal dander) of food particles during vomiting, herbicides or fluorocarbons and some systemic diseases.

It is distinguished from pneumonia on the basis of causation as well as its manifestation since pneumonia can be described as pneumonitis combined with consolidation and exudation of lung tissue due to infection with microorganism.

Causes

• Viral infection. Measles can cause severe pneumonitis, and ribavirin has been proposed as a possible treatment. CMV is another cause.
• Pneumonia
• Radiation therapy
• Inhaling chemicals, such as sodium hydroxide
• Interstitial lung disease
• Sepsis
• Adverse reaction to medications
• Hypersensitivity to inhaled agents
• Inhalation of spores of some species of mushroom (bronchoalveolar allergic syndrome)
• Mercury exposure
• Smoking
• Overexposure to chlorine
• Bronchial obstruction (obstructive pneumonitis or post-obstructive pneumonitis)
• Ascariasis (during parasite migration)

Diagnosis

A chest X-ray or CT is necessary to differentiate between pneumonitis and pneumonia of an infectious etiology. Some degree of pulmonary fibrosis may be evident in a CT which is indicative of chronic pulmonary inflammatory processes.

Classification

It can be classified into acute interstitial pneumonitis, blood pneumonitis, lymphocytic interstitial pneumonitis, radiation pneumonitis, and uremic pneumonitis.

Treatment

Typical treatment for pneumonitis includes conservative use of corticosteroids such as a short course of oral prednisone or methylprednisolone. Inhaled corticosteroids such as fluticasone or budesonide may also be effective for reducing inflammation and preventing re-inflammation on a chronic level by suppressing inflammatory processes that may be triggered by environmental exposures such as allergens.

See also

• Hypersensitivity pneumonitis, also known as extrinsic allergic alveolitis (EAA)