A Case of Autopsy-Proven Exogenous Lipoid Pneumonia in a 100-Year-Old Woman: An Unexpected Complication of Sputum Suction.

Abstract

To the Editor: Exogenous lipoid pneumonia (ELP) is an unusual and preventable illness in elderly adults. Inhalation or aspiration of lipid materials, most commonly mineral oil, causes it. Owing to its nonspecific clinical presentation and radiological features, diagnosis of ELP is often missed or delayed. This letter illustrates the case of autopsy-proven exogenous lipoid pneumonia in a 100-year-old woman who underwent frequent sputum suction with catheters lubricated with oil-based nasal drops in a supine position for 10 months. A large amount of liquid paraffin was aspirated, which was presumed to cause ELP. Healthcare practitioners should increase awareness to avoid iatrogenic complication. A 100-year-old woman with chronic bronchitis, hypertension, coronary heart disease, hyperlipemia and impaired glucose tolerance was stared on continuous nasogastric feeding of enteral nutritional emulsion on January 1, 2013, because of anorexia. She had experienced repeated onset of fever for the previous 2 years and vomited occasionally. Serial chest radiographs demonstrated patches in the right lower lobe that indicated aspiration pneumonia, and antibiotics were effective. She had been completely bed-ridden since April 2014, since when mild carbon dioxide retention occurred intermittently because of dysexpectoration, and she had sputum suction from three to eight times per day. Oil-based nasal drops consisting of menthol and liquid paraffin were used to lubricate the suction catheters to alleviate nasal mucous injury and epistaxis. She had a fever again on December 28, 2014. Chest radiograph revealed bilateral pulmonary infiltrates. Sputum cultures demonstrated the presence of Pseudomonas aeruginosa and Klebsiella pneumoniae. Serological tests for pertinent viruses and fungi were within normal limits. She was treated for bacterial infection with broad-spectrum antibiotics, but she remained febrile intermittently with copious purulent sputum production, which resulted in more-frequent sputum suction. Large amounts of oil-based nasal drops were used to lubricate suction catheters during that period. In February 16, 2015, capillary blood gas values obtained while she was undergoing bilevel positive airway pressure therapy using a noninvasive ventilator were pH, 6.9; partial pressure of carbon dioxide, 185 mmHg; and partial pressure of oxygen, 46 mmHg. She died that day. An autopsy was performed, and pathological examination showed “lipid-laden histiocytes filling up the bronchioles and interstitial spaces consistent with lipoid pneumonia. Oil-red-O stain showed diffuse lipid deposition. Mild interstitial fibrosis was also present.” The cause of death was type II respiratory failure secondary to bilateral diffuse lipoid pneumonia. Exogenous lipoid pneumonia is an uncommon form of pneumonia caused by inhalation or aspiration of lipid materials, most commonly mineral oil.1 It occurs mostly in elderly adults and in children with local anatomical defects, presumably because these groups are more prone to aspiration.2 Acute ELP occurs after aspirating a large volume of a fatty substance, whereas chronic ELP occurs with repetitive aspiration of lipid materials. Aspiration may be occupation related (e.g., fire-eater) or due to habits such as repeated use of oil-based laxatives or nasal drops, lip balm, and petroleum jelly.3-6 The woman described herein experienced frequent sputum suction in supine position with catheters lubricated using oil-based nasal drops for 10 months. A large amount of liquid paraffin was aspirated, which was presumed to have caused ELP. The usual presentation occurs with insidious onset and nonspecific respiratory symptoms such as cough, dyspnea, and fever.4 High-resolution computed tomography (CT) is the best imaging modality for the diagnosis of lipoid pneumonia. The most characteristic CT finding is negative attenuation values within areas of consolidation,7 although the radiological appearance of the disorder can mimic many other lung diseases, including carcinoma.8 Owing to the nonspecific clinical presentation and radiological features, diagnosis of this disease requires a high index of suspicion and can be confirmed by detecting intra-alveolar lipid and lipid-laden macrophages in respiratory specimens. The treatment of ELP is not well defined, beyond avoiding ongoing exposure and providing supportive care. Aggressive therapies, including lung lavage, systemic corticosteroids, immunoglobulins, and surgical resection, have been reported in individuals with diffuse pulmonary damage.9, 10 The diagnosis of ELP is often missed or delayed. Greater awareness could help with diagnosis and prevention efforts. Lubricating sputum suction catheters with lipid materials should be discouraged in routine clinical practice to avoid iatrogenic complications. Conflict of Interest: The authors have no financial or any other kind of personal conflicts with this paper. Author Contributions: All authors contributed to this paper. Sponsor's Role: None.