LIPOID PNEUMONIA: A RARE CASE

Abstract

SESSION TITLE: Fellows Lung Pathology Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: October 18-21, 2020 INTRODUCTION: Lipoid pneumonia is an uncommon entity without specific imaging features or clinical presentation. On chest computerized tomography (CT) it may appear as consolidation, ground-glass opacities (GGO), "crazy-paving” pattern, or a mass. Management requires sampling for histopathologic diagnosis. CASE PRESENTATION: An 87-year old asymptomatic man with remote history of smoking 47 pk/yr, enrolled in the lung nodule clinic for lung surveillance, had redemonstrations of right-sided subsolid pulmonary nodules. The largest of these nodules in the right upper lobe measured 3.4 cm and was suspicious for a low-grade cystic adenocarcinoma. His health history includes history of prostate carcinoma, positive for fecal blood, essential, benign hypertension, hyperlipidemia, GERD and eczema. Review of systems was negative. He underwent bronchial brush, BAL and transbronchial biopsy lesion. The cytology and surgical pathology specimens consistently found lipoid pneumonia. NO further sampling was indicated DISCUSSION: Lipoid pneumonia may be endogenous (EnLP) or exogenous (ExLP). While EnLP is typically due to an accumulation of lipid-containing macrophages distal to an area of obstruction, infection, or lipid storage disease, ExLP results from ingestion and aspiration of foreign material, with mineral oil, often used as a laxative . Patients with chronic lipoid pneumonia (CLP) are usually asymptomatic. Radiologically CLP frequently displays GGO or consolidative opacities involving one or more segments with a peribronchovascular distribution and predominant involvement of the lower lobes. Architectural distortion with the consolidative opacities has been reported and thickening of the interlobular septa or fibrosis in the adjacent lungs can occur due to the transportation of oils from the alveoli into the lung interstitium. GGO with associated interlobular septal thickening with a basilar predominance have also been described. The morphology of ExLP, in the case of mineral oil, is attributed to the inability of enzymes to metabolize the non-saponifiable substances that are absorbed by macrophage. Cytologically, lipoid pneumonia is characterized by proliferation of foamy histiocytes that show innumerable intracytoplasmic microvesicles. Imaging of cystic infiltrates in the RUL was concerning for adenocarcinoma and sampling via tip-tracking with bronchial brush and biopsy obtained cytology and surgical material. BAL was also performed. The cellular cytology smears and cellblock showed an abundance of multivacuolated histiocytes, also seen in the BAL specimen. The background consisted of reactive bronchial cells with mild atypia, and tridimensional bronchial cell clusters. The cyto/histology appearance is consistent with ExLP. CONCLUSIONS: In this patient's case, the etiology may be related to laxative use. Histologic and cytologic sampling was necessary to rule out malignancy, arrive to the correct diagnosis. Reference #1: 1. Sung S, Tazelaar HD, Crapanzano JP, Nassar A, Saqi A. Adult exogenous lipoid pneumonia: A rare and underrecognized entity in cytology - A case series. Cytojournal. 2018;15:17. Published 2018 Jul 13. https://doi.org/10.4103/cytojournal.cytojournal_29_17 Reference #2: 2. Betancourt SL, Martinez-Jimenez S, Rossi SE, Truong MT, Carrillo J, Erasmus JJ. Lipoid Pneumonia: Spectrum of Clinical and Radiologic Manifestations. American Journal of Roentgenology 2010 194:1, 103-109 Reference #3: 3. Baron SE, Haramati LB, Rivera VT. Radiological and clinical findings in acute and chronic exogenous lipoid pneumonia. J Thorac Imaging. 2003;18(4):217-224. https://doi.org/10.1097/00005382-200310000-00002 DISCLOSURES: No relevant relationships by Yazeed Alwelaie, source=Web Response No relevant relationships by Eric Flenaugh, source=Web Response No relevant relationships by Gabriela Oprea-Ilies, source=Web Response No relevant relationships by James Roberts, source=Web Response