TOPIC: Lung Pathology
TYPE: Medical Student/Resident Case Reports
INTRODUCTION: Diffuse alveolar damage (DAD) is considered the histological hallmark of the acute phase of acute respiratory distress syndrome (ARDS), a life-threatening pulmonary condition (1). It is characterized by edema and hyaline membranes (1). One distinction in COVID-19 associated DAD is the involvement of massive capillary microthrombi (2). We present a case of a patient with DAD and acute thrombosis on tissue biopsy consistent with COVID-19 infection despite multiple negative COVID tests.
CASE PRESENTATION: A 51 year old non-smoker male with no pulmonary history presented to the hospital for eight day history of dyspnea. He was a factory worker with exposures to flour and sugar dust. On admission, he was febrile, tachycardic, and tachypneic with diffuse lung crackles. Computed Tomography (CT) Angiogram of the chest was negative for pulmonary embolism but showed bilateral lung opacities. Nasopharyngeal swab was negative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). He was treated with empiric intravenous antibiotics. His condition deteriorated and he was transferred to the intensive care unit (ICU). He was found to have ARDS and was intubated, proned and started on IV steroids. He developed intermittent fevers and worsening airspace opacities on pulmonary imaging. He underwent two bronchoscopies with bronchoalveolar lavage (BAL). BAL cultures were negative for bacterial, fungal, or viral species. Cytology was negative for malignant cells. Vasculitis and autoimmune workup were unrevealing. He underwent video assisted thoracoscopic surgery (VATS) with lung wedge biopsy which revealed diffuse alveolar damage with acute vascular thrombosis most compatible with COVID pneumonia. However, he had four negative nasopharyngeal swabs for SARS-CoV-2. He continued to receive high dose steroids, was successfully extubated and subsequently discharged to an acute rehabilitation center. On follow up visit, his CT scan of the chest showed mild to moderate scarring and pulmonary function tests showed moderate degree of restrictive defect. While his pathology results were not fully consistent with hypersensitivity pneumonitis (3) he was advised to avoid his factory job.
DISCUSSION: Diffuse alveolar damage is a major cause of morbidity and mortality (1). Microthrombi can be a feature of DAD in the setting of viral pneumonias such as COVID-19, though it does not remain exclusive to COVID-19 (3). However, as the pathophysiology of this novel virus is not completely understood, it remains on the differential.
CONCLUSIONS: This case exemplifies the importance of maintaining a broad differential diagnosis when evaluating etiology of ARDS, particularly in the setting of an ongoing pandemic involving a novel virus. Additionally, pathologists should be aware of alternate lung histology patterns as this may influence treatment decisions and disease outcomes.
REFERENCE #1: Cardinal-Fernández, P., Lorente, J. A., Ballén-Barragán, A., & Matute-Bello, G. (2017). Acute Respiratory Distress Syndrome and Diffuse Alveolar Damage. New Insights on a Complex Relationship. Annals of the American Thoracic Society, 14(6), 844–850. https://doi.org/10.1513/AnnalsATS.201609-728PS
REFERENCE #2: Menter, T., Haslbauer, J. D., Nienhold, R., Savic, S., Hopfer, H., Deigendesch, N., Frank, S., Turek, D., Willi, N., Pargger, H., Bassetti, S., Leuppi, J. D., Cathomas, G., Tolnay, M., Mertz, K. D., & Tzankov, A. (2020). Postmortem examination of COVID-19 patients reveals diffuse alveolar damage with severe capillary congestion and variegated findings in lungs and other organs suggesting vascular dysfunction. Histopathology, 77(2), 198–209. https://doi.org/10.1111/his.14134
REFERENCE #3: Riario Sforza, G. G., & Marinou, A. (2017). Hypersensitivity pneumonitis: a complex lung disease. Clinical and molecular allergy : CMA, 15, 6. https://doi.org/10.1186/s12948-017-0062-7
DISCLOSURES: No relevant relationships by Bao Nhi Nguyen, source=Web Response
No relevant relationships by Navitha Ramesh, source=Web Response