Pneumonitis describes general inflammation of lung tissue. Possible causative agents include radiation therapy of the chest, exposure to medications used during chemo-therapy, the inhalation of debris (e.g., animal dander), aspiration, herbicides or fluorocarbons and some systemic diseases. If unresolved, continued inflammation can result in irreparable damage such as pulmonary fibrosis.Pneumonitis is distinguished from pneumonia on the basis of causation as well as its manifestation. Pneumonia can be described as pneumonitis combined with consolidation and exudation of lung tissue due to infection with microorganisms. The distinction between Pneumonia and Pneumonitis can be further understood with Pneumonitis being the encapsulation of all respiratory infections (incorporating pneumonia and pulmonary fibrosis as major diseases), and pneumonia as a localized infection. For most infections, the immune response of the body is enough to control and apprehend the infection within a couple days, but if the tissue and the cells cant fight off the infection, the creation of pus will begin to form in the lungs which then hardens into lung abscess or suppurative pneumonitis. Patients that are immunodeficient and dont get treated immediately for any type of respiratory infection may lead to more severe infections and/or death.Pneumonitis can be classified into several different specific subcategories, including hypersensitivity pneumonitis, radiation pneumonitis, acute interstitial pneumonitis, and chemical pneumonitis. These all share similar symptoms, but differ in causative agents. Diagnosis of pneumonitis remains challenging, but several different treatment paths (corticosteroids, oxygen therapy, avoidance) have seen success. Causes
Alveoli are the primary structure affected by pneumonitis.
Symptoms usually appear a few hours after exposure and peak at approximately eighteen to twenty-four hours.Other symptoms may include:

Malaise
Fever
Dyspnea
Flushed and/or discolored skin
Sweating
Small and fast inhalationsWithout proper treatment, pneumonitis may become chronic pneumonitis, resulting in fibrosis of the lungs and its effects:

Difficulty breathing
Food aversion
LethargyEnd-stage fibrosis and respiratory failure eventually lead to death in cases without proper management of chronic pneumonitis. 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. Diagnosis of Pneumonitis is often difficult as it depends on a high degree of clinical suspicion when evaluating a patient with a recent onset of a possible interstitial lung disease. In addition, interpreting pathologic and radiographic test results remains a challenge to clinicians. Pneumonitis is often difficult to recognize and discern from other interstitial lung diseases.Diagnostic procedures currently available include:

Evaluation of patient history and possible exposure to a known causative agent
High-Resolution Computed Tomography (HRCT) consistent with pneumonitis
Bronchoalveolar lavage with lymphocytosis
Lung biopsy consistent with pneumonitis histopathologyExposure to causative agents of pneumonitis in a specific environment can be confirmed through aero/microbiologic analysis to verify its presence. Subsequent testing of patient serum for evidence of serum specific IgG antibodies confirms patient exposure.Clinical tests include chest radiography or (HRCT) which may show centrilobular nodular and ground-glass opacities with air-trapping in the middle and upper lobes of the lungs. Fibrosis may also be evident.