Eosinophilic pneumonia is a disease in which an eosinophil, a type of white blood cell, accumulates in the lungs. These cells cause disruption of the normal air spaces (alveoli) where oxygen is extracted from the atmosphere. Several different kinds of eosinophilic pneumonia exist and can occur in any age group. The most common symptoms include cough, fever, difficulty breathing, and sweating at night. Eosinophilic pneumonia is diagnosed by a combination of characteristic symptoms, findings on a physical examination by a health provider, and the results of blood tests and X-rays. Prognosis is excellent once most eosinophilic pneumonia is recognized and treatment with corticosteroids is begun. Classification
Eosinophilic pneumonia is divided into different categories depending upon whether its cause can be determined or not. Known causes include certain medications or environmental triggers, parasitic infections, and cancer. Eosinophilic pneumonia can also occur when the immune system attacks the lungs, a disease called eosinophilic granulomatosis with polyangiitis. When a cause cannot be found, the eosinophilic pneumonia is termed "idiopathic". Idiopathic eosinophilic pneumonia can also be divided into acute and chronic forms, depending on the symptoms a person is experiencing. Signs and symptoms
Most types of eosinophilic pneumonia have similar signs and symptoms. Prominent and nearly universal signs and symptoms include cough, fever, difficulty breathing, and night sweats. Acute eosinophilic pneumonia typically follows a rapid course. Fever and cough may develop only one or two weeks before breathing difficulties progress to the point of respiratory failure requiring mechanical ventilation. Chronic eosinophilic pneumonia usually follows a slower course.
Diagnosis
Eosinophilic pneumonia is diagnosed in one of three circumstances: when a complete blood count reveals increased eosinophils and a chest X-ray or computed tomography identifies abnormalities in the lungs, when a biopsy identifies increased eosinophils in lung tissue, or when increased eosinophils are found in fluid obtained by a bronchoscopy (bronchoalveolar lavage fluid). Association with medication or cancer is usually apparent after review of a persons medical history. Specific parasitic infections are diagnosed after examining a persons exposure to common parasites and performing laboratory tests to look for likely causes. If no underlying cause is found, a diagnosis of acute or chronic eosinophilic pneumonia is made based upon the following criteria. Acute eosinophilic pneumonia is most likely with respiratory failure after an acute febrile illness of usually less than one week, changes in multiple areas and fluid in the area surrounding the lungs on a chest X-ray, and eosinophils comprising more than 25% of white blood cells in fluid obtained by bronchoalveolar lavage. Other typical laboratory abnormalities include an elevated white blood cell count, erythrocyte sedimentation rate, and immunoglobulin G level. Pulmonary function testing usually reveals a restrictive process with reduced diffusion capacity for carbon monoxide. Chronic eosinophilic pneumonia is most likely when the symptoms have been present for more than a month. Laboratory tests typical of chronic eosinophilic pneumonia include increased levels of eosinophils in the blood, a high erythrocyte sedimentation rate, iron deficiency anemia, and increased platelets.