WHERE DID THE HISTIOCYTES COME FROM? A CASE OF DIFFUSE LUNG INFILTRATES WITH HISTIOCYTOSIS IN BRONCHOALVEOLAR LAVAGE

Abstract

SESSION TITLE: Wednesday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/23/2019 09:45 AM - 10:45 AM INTRODUCTION: Analyzing bronchoalveolar lavage (BAL) fluid provides useful information for diffuse bilateral pulmonary infiltrates with unclear etiologies. We report a case of bilateral interstitial lung disease with histiocytes predominant in BAL in an otherwise healthy female. CASE PRESENTATION: 59 y/o female, never smoked, with no significant past medical history who presented with persistent cough of 2 months. She denied weight loss, night sweats, fever, chills, chest pain, shortness of breath, sick contacts, travel. Physical exam is unremarkable. Initial labs showed neutrophilic predominant leukocytosis. Chest x-ray showed patchy right lower lobe infiltrates. CT chest revealed diffuse bilateral pulmonary parenchymal abnormalities and mildly enlarged right paratracheal and right hilar lymph nodes. The patient underwent bronchoscopy and bronchoalveolar lavage (BAL), cultures grew alpha strep and Capnocytophaga species, BAL cytology revealed mainly histiocytes( 98%). Further testing negative for: influenza, tuberculosis, fungal panel, urine Legionella. Positive for Mycoplasma antibody IgG. She was treated for community acquired pneumonia with ceftriaxone and azithromycin with good clinical response. Patient had a repeat chest x-ray 2 weeks later which showed resolution of her right sided infiltrates, and blood work revealing restoration of leukocytosis. She reported improvement of her symptoms. All of these indicating resolution of her right sided pneumonia. DISCUSSION: Histiocytes are part of the mononuclear phagocyte system aka the reticuloendothelial system. In normal circumstances, histiocytes are mainly found as pulmonary alveolar macrophages. However, they actively participate in all inflammatory reactions of the lung. In some cases, risks factors like smoking could predispose patients to a specific histiocytic predominant pathology. Histiocytic pulmonary lesions present as nodular and/or diffuse proliferations in the lung. Pulmonary lesions with histiocytes predominant can be neoplastic, for example- histiocytic sarcoma; or non-neoplastic such as pulmonary Langerhans’ cell histiocytosis, desquamative interstitial pneumonia, pneumoconiosis, infections, diffuse panbronchiolitis, crystal storing histiocytosis, respiratory bronchiolitis, alveolar hemorrhage, eosinophilic pneumonia, obstructive pneumonia, exogenous lipoid pneumonia, some drug reactions, and other metabolic/storage disorders. Our patient presented with atypical pneumonia, cough for 2 months, diffuse interstitial infiltrates with histiocytosis in BAL. IgM for Mycoplasma pneumoniae negative, IgG with high titer. She had good clinical and radiological response with conservative management. CONCLUSIONS: In our case, Mycoplasma pneumoniae was etiology. Multidisciplinary approach and mechanism-based therapeutic strategies are important for diffuse interstitial lung disease with histiocytosis in BAL. Reference #1: Wang, C. and Colby, T. (2007). Histiocytic lesions and proliferations in the lung. Seminars in Diagnostic Pathology, [online] 24(3), pp.162-182. Available at: https://www.ncbi.nlm.nih.gov/pubmed/17882900. Reference #2: Andrea Morelli et al. Effect of Heart Rate Control With Esmolol on Hemodynamic and Clinical Outcomes in Patients With Septic Shock: A Randomized Clinical Trial. JAMA.2013;310(16):1683-1691. https://doi.org/10.1001/jama.2013.278477. Reference #3: Moon J, du Bois RM, Colby TV, et al. Clinical significance of respiratory bronchiolitis on open lung biopsy and its relationship to smoking related interstitial lung disease. Thorax 1999; 54:1009. DISCLOSURES: No relevant relationships by Violeta Alvarez-Retamales, source=Web Response No relevant relationships by Phyo Kyaw, source=Web Response