Pathology of Double Lung Transplantation of 12 Cases Following COVID-19

ABSTRACT

Background: Pulmonary failure is one of the major causes of death in COVID-19 (SARS-CoV-2) patients. Lung transplantation has been evolving to rescue those patients' lives with promising success. Explanted native lungs post COVID-19 are valuable to understand the long-term pulmonary pathology of this deadly disease, as currently available data is very limited. Design: Lung transplantation cases post COVID-19 were collected through the pathology database in our institution from January 2020 through September 2021. Patient clinical courses, CT imaging data prior to transplantation and pathological findings are evaluated. Results: The cohort consisted of 12 male patients with a median age of 46.5 years (range 24 - 67). Co-morbidities were present in 6 patients including obesity, diabetes mellitus and hypertension. No prior known pulmonary specific disease was present in any of the patients. Extracorporeal membrane oxygenation (ECMO) was used in 10 of 12 patients for 54 - 130 days. CT imaging pretransplantation showed extensive bilateral consolidation (5 cases), extensive bilateral ground-glass (3 cases) or extensive infiltration/air space disease (4 cases). All patients survived post double lung transplantation (including one patient with concurrent heart transplantation) and no significant pathologic alteration was identified on most recent surveillance biopsies (26 - 183 days post transplantation). The most prominent pathological finding in the explanted lungs is nonspecific interstitial pneumonia (NSIP)- like interstitial fibrosis (100%, 12 cases). Other findings include collections of numerous hemosiderin-laden macrophages (8 cases), patchy diffuse alveolar damage (DAD) (hyaline membrane formation and/or organizing DAD) (5 cases), intrapulmonary small vessel thrombosis (5 cases), organizing pneumonia (5 cases), necrosis (2 cases), calcifications (5 cases), acute pneumonia (3 cases), peribronchiolar metaplasia (8 cases), and microscopic honeycombing (8 cases). No viral cytopathic changes were seen. The pathologic findings of the two patients who did not receive ECMO are similar to those in patients with variable length of ECMO treatment. Conclusions: Lung transplantation is a successful treatment option for eligible candidates with pulmonary fibrosis and failure post COVID-19. NSIP-like interstitial fibrosis is a universal finding, consistent with a sequala of DAD. A spectrum of acute, subacute, vascular and airway-related changes are also prominent findings in respiratory failure post COVID-19.