INTRODUCTION: Lipoid pneumonia is an uncommon lung disorder and was first described by Laughlen in 1925¹. It has 2 forms, exogenous and endogenous. Diagnosis is difficult and challenging because this condition is known to mimic many pulmonary diseases clinically and radiographically. We present a very rare case with a diagnosis of endogenous lipoid pneumonia (ELP) resulted from pancreatobiliary cancer.
CASE PRESENTATION: An 80 year-old-man, smoker, with no significant co-morbidities presented to ER with dyspnea, cough, and low grade fever. His Chest radiograph showed bilateral diffuse consolidation and was treated for community acquired pneumonia. His symptoms persisted and was later admitted for weight loss and painless jaundice. Initial workup revealed elevated liver enzymes with total bilirubin of 6.6 mg/dl, AST 215 U/L, ALT 260 U/L and ALP 686 U/L. To clarify the cause of the cholestasis, magnetic resonance cholangio-pancreatography was done which revealed distended gall bladder with dilated intra and extrahepatic ducts and stenosed distal common bile duct. ERCP was performed with sphinterotomy, cholangiogram, brushings and biopsy followed by stent placement. Tumor markers showed elevated CA19-9 (1132U/ML) but normal CEA and AFP. Biopsy results were nondiagnostic.He was noted to have bronchorrhea and worsening of bilateral consolidation on chest radiograph and CT scan suggestive of non resolving pneumonia. The major differential diagnosis of non resolving pneumonia in this gentleman included BAC (Broncho-Alveolar carcinoma) and organizing pneumonia considering overall clinical picture and characteristic CT chest findings of bilateral diffuse airspace opacities with air bronchograms in peripheral distribution. Fiber-optic bronchoscopy was done; cytological examination of the lavage-fluid, to our surprise, showed predominantly lipid laden macrophages containing fatty vesicles, characteristic for lipoid pneumonia. Histological examination of transbronchial lung biopsy sample showed mild interstitial inflammation, without signs of malignancy or other interstitial lung disease. The patient denied mineral oil ingestion, aspiration or swallowing problems. He was therefore diagnosed with ELP and we recommended VATS lung biopsy to ascertain etiology of his ELP.A surgical lung biopsy was then performed which revealed diffusely involved metastatic adenocarcinoma consistent with pancreatobiliary primary confirmed with immunohistochemical markers: TTF-1 negative, positive CK-7 and CK-20, strongly positive for CA 19-9. It also showed a background benign lung with air spaces filled with lipid laden macrophages highly suggestive of lipoid pneumonia. Considering metastatic cancer, he opted for palliative care.
DISCUSSIONS: ELP also called "cholesterol pneumonia" or golden pneumonia", typically manifests as an obstructive pneumonitis containing lipid distal to a centrally located mass. It is a histopathologic diagnosis and is due to tissue destruction and release of tissue lipids that are phagocytized by macrophages. It usually occurs as a result of bronchial occlusion from primary lung cancers. The transbronchial dissemination of breakdown products of adenocarcinoma cells, including mucin, may contribute to the spread of non obstructing component of ELP. Chest radiography changes can be very non specific ranging from consolidative changes, cysts to ground glass appearance producing ’crazy paving pattern’². Histopathologically, the differential diagnosis of ELP is particularly with mucinous adenocarcinoma and few other conditions are Gaucher’s disease and amiodarone induced lung toxicity. Several other entities, including pulmonary infections, lipid storage disorders, and pulmonary alveolar proteinosis are considered within the spectrum of ELP.
CONCLUSION: There have been case reports of metastatic mucinous adenocarcinomas of gastrointestinal origin mimicking BAC, pulmonary nodules and airspace pattern. Although, adenocarcinoma of the GI tract is a rare cause of lipoid pneumonia, our case further illustrates this unusual presentation and warrants to look for such malignancies in the presence of ELP.
DISCLOSURE: Sridhar Badireddi, No Financial Disclosure Information; No Product/Research Disclosure Information