A rare case of acute eosinophilic pneumonia

Acute eosinophilic pneumonia (AEP) has been described as an acute febrile illness with severe hypoxemia, diffuse pulmonary infiltrates, and an increase in bronchoalveolar lavage eosinophils. There is also no evidence of infection, no history of asthma or atopic illness, and complete resolution of all abnormalities after treatment with corticosteroids. ^[1] It is a reversible cause of non-infectious respiratory failure. ^[1],[2] AEP is a rare disorder, and less than 100 cases have been reported to date, with the largest series including only 15 patients. ^[3],[4] We report a case, which had features of AEP with no radiological evidence of pulmonary infiltrates.

Keywords: Acute eosinophilic pneumonia, BAL eosinophils, steroid

Acute Eosinophilic Pneumonia is a rare disorder and diagnosis of exclusion. Less than 100 cases have been reported to date, with the largest series including only 15 patients. Authors report a case of a 24-year-old male who presented with one-day history of high-grade fever, progressive dyspnea, bilateral pleuritic chest pain, and non-productive cough and was subsequently found to be suffering from Acute Eosinophilic Pneumonia and was started on steroids and responded well to treatment.

A 24-year-old male presented with one-day history of high-grade fever, progressive dyspnea, bilateral pleuritic chest pain, and non-productive cough. On examination, his pulse rate was 90/min, respiratory rate 20/min, and blood pressure was 120/70 mm Hg. He had bibasilar crackles. Rest of the examination was within normal limits.

Investigations

Laboratory tests were normal except for a total leukocyte count of 33,300 cells/mm ³ with differentials of 8% neutrophils, 1% lymphocytes, 1% basophils, and 90% eosinophils. His arterial blood gas showed pH 7.41, Pao ₂ 62.6 mm Hg, Paco ₂ 32.9 mm Hg, HCO ₃ 20.3 mmol/L, and O ₂ saturation 92.5%. He was treated with oxygen and oral prednisolone 60 mg every 6 hours for 3 days, and then 60 mg daily. Blood and urine culture were negative. Chest radiograph and HRCT chest were normal. BAL recovered 620,000 cells/ml with differential of 65% eosinophils, 20% macrophages, 9% lymphocytes, and 6% neutrophils. His total IgE level was 64 ng/ml. Pulmonary function test showed: FVC 2.25 L (59%), FEV 1.68 (51%), expiratory flow at 50% FVC 1.51 L/second (31%).

Treatment

He was started on corticosteroids and after treatment with corticosteroids for 15 days, the arterial blood gas analysis improved and showed pH 7.47, Pao ₂ 101 mm Hg, Paco ₂ 32.7 mm Hg, HCO ₃ 23.1 mmol/L, and O ₂ saturation 97.9%. His repeat total leukocyte count was 9000 cells/mm ³ with differential of 63% neutrophils, 33% lymphocytes, 2% monocytes, and 2% eosinophils.

Outcome and Follow-up

He was continued on oral prednisone for 3 weeks; following this, he became asymptomatic.

AEP is a diagnosis of exclusion. The following diagnostic criteria have been suggested: ^[1] Acute febrile illness of < 5 to 7 days’ duration, ^[2] hypoxemic respiratory failure, ^[3] diffuse mixed alveolar, and interstitial chest radiographic infiltrates, ^[4] bronchoalveolar lavage (BAL) eosinophilia (> 25%), ^[5] no apparent infectious cause, ^[6] rapid and complete response to corticosteroid therapy, and ^[7] no relapse after discontinuation of corticosteroid therapy. ^[1],[4] Peripheral blood eosinophil percentage are usually normal, although they can be slightly elevated in a minority of patients. In striking contrast to blood eosinophil percentages, a very high percentage of BAL eosinophils is characteristic with an average of 42% reported. ^[1] The percentages of lymphocytes and neutrophils in BAL fluid are also elevated in many patients. Serum IgE levels have been elevated in some but not in all patients. The chest radiograph generally shows bilateral diffuse infiltration on non-segmental distribution, which may initially exhibit an interstitial pattern and progress to alveolar infiltration. ^[1] The presence of Kerley B lines early in the presentation can be an important diagnostic clue. ^[1],[4] Pulmonary function studies in the acute phase show a low diffusing capacity and restriction. ^[1] Our case fulfilled majority of the diagnostic criteria of AEP without any evidence of pulmonary infiltrates on chest radiograph as well as on high resolution computed tomography (HRCT) of the chest. This can be explained by very early presentation of disease or mild exposure by causative agent, which is also supported by few case series. ^[5],[6],[7]

Any patient who present with acute respiratory symptoms, the diagnosis of AEP should be considered apart from common illness, which can widen the spectrum of these disorders in developing countries so that future research can be undertaken.

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1755-6783.116505