Dr. Parul Sharma ACUTE EO...

  Acute Eosinophilic Pneumonia Presenting as Life Threatening ARDS and Right Sided Massive Pleural Effusion- A Rare Case Report.

Introduction :
- Acute eosinophilic pneumonia (AEP) is an uncommon, acute respiratory illness of varying severity, characterized by the presence of diffuse pulmonary infiltrates.
- Frequently misdiagnosed as CAP.
- Often presents as and is indistinguishable from Acute respiratory distress syndrome (ARDS). 
- May be idiopathic, but identifiable causes include recent smoking, inhalational exposures, medications, and infections. 
- Occurs at any age, but more common in males of  20-40 years. 
- Demonstration of pulmonary eosinophilia in BAL and exclusion of other conditions that can present with acute pulmonary infiltrates confirms diagnosis.
- Cessation of the exposure to the inciting agent and glucocorticoids represent the mainstay of treating AEP.
- If recognized and treated in a timely manner, the prognosis is generally excellent, with prompt and complete clinical recovery, even in those patients manifesting as acute respiratory failure or ARDS. 

Case Report : 
- 60-year-old male, k/c/o CKD, never-smoker, presented to ER in a state of circulatory collapse and severe respiratory distress needing intensive care unit (ICU) admission. 
- He had c/o shortness of breath and dry cough for 7 days along with right sided chest pain for 2 days. 
- Vitals at admission : PR-130/min, RR-46/min, BP-90/60 mmHg and spO2- 60% at room air.
- O/A: bilateral harsh vesicular breath with reduced intensity of breath sound over right hemi-thorax and bilateral extensive rhonchi. 
- Was put on non-invasive mechanical ventilation (NIMV) and vasopressor support. 
- Empiric antibiotic therapy was started (Meropenam and azithromycin) suspecting it to be a case of severe CAP.

On further work up-
- ABG: Type 1 respiratory failure.
- Chest X-ray: bilateral heterogeneous opacity with right massive pleural effusion. 
- Hematological investigation and PCT: Unremarkable.
- Sputum cultures : sterile and negative for MTb.
- Pleural fluid cytology: lymphocytes in background of eosinophilic proteinaceous material with 55% eosinophils in differential count. 
- HRCT (thorax): multifocal patches of pneumonitis in bilateral lung fields and right sided hydro-pneumothorax, that was iatrogenic.
- NIMV was withdrawn and patient was kept on high flow oxygen therapy.
- In view of ruling out AEP, bronchoscopy was performed in the ICU after taking proper consent. 
- BAL cytology also showed lymphocytes in background of eosinophilic proteinaceous material and BAL differential showed marked eosinophilia (30%). 
- Hence, the diagnosis of Acute Eosinophilic Pneumonia was established.
- Started on pulse steroid therapy with methyl-prednisolone (125 mg every 6 hours).
- Next day, no longer needed vasopressors and two days later, oxygenation and clinical status improved markedly. 
- Follow up Chest X ray and CT scan showed radiological clearing.
- Patient was shifted from ICU to ward for continuation of care. 
- Five days, was discharged on oral prednisolone which was gradually tapered. 
- He returned for follow-up in OPD with no significant limitation.

Discussion: 
- Approximately, 100 cases of AEP have been described in literature till date.
- Rare disease that can rapidly progress to respiratory failure.
- If identified and managed early, the clinical response to treatment is prompt and complete, without long-term consequences. 
- Most common presenting signs and symptoms, in decreasing order, are fever, dyspnea, and cough.
- Temporal relation between development of AEP and inciting factors such as heavy dust exposure, drugs, occupational exposures and cigarette smoking seen, but idiopathic in most patients. 
- Key features in diagnosis: respiratory impairment, diffuse pulmonary infiltrates on X-ray, peripheral ground glass opacities and diffuse bilateral reticular densities, with septal thickening and pleural effusions on HRCT. and BAL eosinophilia. 
- Steroids are the gold standard of treatment.

Take Home Message:
- AEP should always be considered in patients who present with ARDS.
- Most predisposing factor leading to a delayed diagnosis of AEP is the fact that it is a rare disease. Overlapping pictures with bacterial/fungal pneumonia add to the diagnostic dilemma; hence, treating broadly at presentation is not unreasonable.
- When patients present with refractory hypoxemic respiratory failure despite appropriate antibiotic treatment and ventilator support, a differential of AEP should be kept in mind.
- So, besides infection as a cause of ARDS, one should always keep in mind other inflammatory lung diseases that prompt entirely different therapy. 
- While AEP dramatically responds with steroid therapy, the same when given in an infective cause may lead to disease flare up, highlighting the importance of early and accurate diagnosis with early institution of adequate therapy to obviate unnecessary morbidity and mortality associated with ARDS.