474 PRACTITIONERS’ SECTION LIPOID PNEUMONIA: AN UNCOMMON ENTITY G. C. KHILNANI, V. HADDA ABSTRACT Lipoid pneumonia is a rare form of pneumonia caused by inhalation or aspiration of fat-containing substances like petroleum jelly, mineral oils, certain laxatives, etc. It usually presents as an insidious onset, chronic respiratory illness simulating interstitial lung diseases. Rarely, it may present as an acute respiratory illness, especially when the exposure to fatty substance(s) is massive. Radiological findings are diverse and can mimic many other diseases including carcinoma, acute or chronic pneumonia, ARDS, or a localized granuloma. Pathologically it is a chronic foreign body reaction characterized by lipid-laden macrophages. Diagnosis of this disease is often missed as it is usually not considered in the differential diagnoses of community-acquired pneumonia; it requires a high degree of suspicion. In suspected cases, diagnosis may be confirmed by demonstrating the presence of lipid-laden macrophages in sputum, bronchoalveolar lavage fluid, or fine needle aspiration cytology/biopsy from the lung lesion. Treatment of this illness is poorly defined and constitutes supportive therapy, repeated bronchoalveolar lavage, and corticosteroids. Key words: Lipid-laden macrophages, lipoid pneumonia, mineral oil aspiration DOI: 10.4103/0019-5359.57639 PMID: 19901490 INTRODUCTION like parafÞ noma, cholesterol pneumonia, lipid granulomatosis, all denoting its association Lipoid pneumonia (LP) is a rare form of with the inhalation or ingestion of various pneumonia caused by inhalation or aspiration substances like petroleum jelly, mineral oils, of a fatty substance. It was Þ rst described in “nasal drops,” and even intravenous injection of 1925 by Laughlin and later by others in the olive oil.[5-13] Many of us are unfamiliar with this Þ rst half of the twentieth century.[1-4] Since then, condition, a fact that may be responsible for the there are many reports with different names underdiagnosis of LP. This entity does not have characteristic clinical or radiological features, Department of Medicine, All India Institute of Medical which makes its diagnosis difÞ cult, unless it is Sciences, New Delhi-110 029, India. already suspected. Therefore, awareness of Correspondence: this type of pneumonia is important. Making Dr. G.C. Khilnani Department of Medicine, a diagnosis of LP requires a high degree of All India Institute of Medical Sciences, clinical suspicion. It should be considered in New Delhi-110 029, India. E-mail: [email protected] the differential diagnoses of many pulmonary Indian J Med Sci, Vol. 63, No. 10, October 2009 LIPOID PNEUMONIA 475 conditions, especially in cases with history of The usual presentation of LP is an insidious exposure to fatty substances. Importantly, if onset of dyspnea and/or cough, similar to those diagnosed in a timely manner, the progression of other chronic lung diseases. Less commonly may be halted or at least slowed by stopping described clinical features include chest pain, the exposure to the offending agent. Once hemoptysis, and intermittent fever which may suspected, diagnosis can be established by be related to the inß ammatory reaction to oil, demonstrating the presence of lipid-laden or which may be secondary to infection.[22] macrophages in various specimens such as Systemic symptoms are uncommon unless sputum, bronchoalveolar lavage, and lung chronic hypoxia precipitates weight loss due to biopsy. The aim of this review is to increase chronically increased work of breathing. Physical awareness of this uncommon entity among examination Þ ndings may be unremarkable or physicians. there may be dullness detected on percussion, crackles, wheezes, or rhonchi. With progressive, CLINICAL FEATURES longstanding disease, physical Þ ndings related to chronic hypoxia can develop. Pulmonary Lipoid pneumonia is an unusual cause of function tests results have shown a restrictive respiratory symptoms and has been reported pattern but they may also be normal.[22,23] Acute in all age groups. Initial reports of LP presentation simulating infectious pneumonia predominantly included children, often with with fever, with or without cough, is unusual.[24] local anatomic defects like cleft palate, or However, acute presentation with respiratory debilitated adults, but several reports indicate failure has been reported with accidental/ that it can occur in healthy individuals as suicidal massive exposure to mineral oil but not well.[8,14] There are reports of LP associated with submassive exposure or inhalation and in with aspirating or inhaling mineral oil, oil-based children.[25-28] Laboratory test results are usually laxatives, lip balm, lip glow etc.[15,16] Siphoning of normal although leukocytosis and an increased various mineral oils (like diesel) from containers erythrocyte sedimentation rate may occur, is a common practice in India and may be an especially when complicated by infection. important risk factor for LP. Other risk factors RADIOLOGICAL FEATURES described in infants and small children are the use of traditional folk remedies like the use of oily Chest X-ray Þ ndings are diverse and can mimic nasal drops, forceful feeding of animal fats such many other diseases including carcinoma, as “ghee” to establish regular bowel habits, or acute or chronic pneumonia, ARDS, or a transnasal use to treat cough and cold.[17,18] Other localized granuloma.[29-31] A homogenous dense common examples of risk factors for LP are the consolidation, often with air bronchograms, and use of sesame oil to ß ush nasal secretions (in sometimes a Þ ne, “spun glass” appearance may India) and to relieve small bowel obstruction due be appreciated in early disease.[29] Involvement to Ascaris lumbricoides (in Brazil).[19,20] It has also may be diffuse or focal, unilateral or bilateral, been reported after bronchography due to the although unilateral pneumonic consolidation use of dye propyliodone (now rarely performed) with lower lobes predilection is more commonly and nasogastric tube feeding.[21] reported.[29,30,32,33] Occasionally, one may also Indian J Med Sci, Vol. 63, No. 10, October 2009 476 INDIAN JOURNAL OF MEDICAL SCIENCES Þ nd cavitation.[34,35] A reticular pattern may be oil. Mineral oils enter the tracheobronchial observed as the emulsiÞ ed oil leaves the alveoli tree without stimulating cough reflex and and enters the interstitium and lymphatics, impair the mucociliary transport system. creating edema, inß ammation, and Þ brosis in Therefore, once inside the alveoli, it is difÞ cult those sites. Fibrosis and coalescence of oil to expectorate the lipid out. This situation can result in nodules and masses with irregular may be complicated by some associated margins, closely mimicking lung cancer.[29,30] neurological and gastrointestinal disorders Atelectasis and pleural effusion have also that affect swallowing and the palatal or cough been described.[22,32,34] CT scan and magnetic reß ex. Once in the alveoli, oil is taken up by resonance imaging can detect fat within macrophages after emulsiÞ cation and because pulmonary tissue. The most commonly described alveolar macrophages cannot metabolize the features are alveolar consolidations [Figures 1a fatty substance, the oil is repeatedly released and b] of low attenuation values (-30 to -150 into the alveoli after the death of the HU), ground glass opacities with thickening macrophages.[43] The oil thus released illicits of intralobular septa (crazy paving pattern), or a giant cell granulomatous reaction (hence, alveolar nodules.[17,36-38] Magnetic resonance LP is also called lipid granulomatosis), chronic imaging may reveal high signal intensity on T1- inflammation, and alveolar and interstitial weighted imaging that is consistent with lipid fibrosis. Evolution of the lesions with time content.[38-42] Lower lobe predominance of the has been described.[41] Fresh lesions show radiographic Þ ndings are often described but not alveolar inÞ ltration by lipid-laden macrophages uniformly seen. and almost normal alveolar walls and septa. Advanced lesions show larger vacuoles PATHOPHYSIOLOGY and inflammatory infiltrates of the alveolar walls, bronchial walls, and septa. Fibrosis Pathologically, LP is a result of a chronic foreign and parenchymal destruction around large body reaction to inhaled/aspirated mineral lipid-containing vacuoles are features of the a b Figure 1: Noncontrast computerized tomographic images of young patients with lipoid pneumonia. Mediastinal, (a) and lung window, (b) showing consolidation in right middle lobe, lower lobe, and also left lung. Few low density areas (arrow) are seen within the middle lobe consolidation. (Reproduced with permission from Biomed Central and Cases Journal) Indian J Med Sci, Vol. 63, No. 10, October 2009 LIPOID PNEUMONIA 477 oldest lesions. Special staining techniques (oil the inflammatory response.[50] However, as red O, Sudan black etc) can more effectively corticosteroids are not to be used routinely, demonstrate that the vacuoles are lipid-Þ lled. The their use is only if the lung injury is severe and speciÞ c type of oil aspirated can be determined ongoing. Other treatment modalities described in by chemical analysis, spectroscopy, and literature are immunoglobins,[51] and whole lung chromatography.[44,45] lavage.[52,53] Repeated bronchoalveolar lavage (BAL) with saline has been shown to be an DIAGNOSIS effective therapeutic modality for the treatment of LP.[28] Some researchers successfully used Diagnosis of LP is