Effusion fluid cytology and COVID-19 infection

Abstract

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is responsible for coronavirus disease 2019 (COVID-19), is known to cause severe respiratory infections with occasional accompanying pleural effusion (PE), pericardial effusion (PCE), or peritoneal effusion (PTE). The effect of COVID-19 on effusion cytology is not yet known. This study aimed to examine the cytomorphologic features and workup of effusion fluids in patients with active COVID-19 infection versus those in recovery. Methods: PE (n = 15), PCE (n = 1), and PTE samples (n = 20) from hospitalized patients with a SARS-CoV-2 infection (from June 1, 2020, to December 30, 2020) were reviewed. Effusion fluids with metastatic carcinoma were excluded. Differential cell counts, cytomorphology, and relevant immunostains for effusion fluids were retrospectively evaluated and compared between patients with active infection (positive on a SARS-CoV-2 nucleic acid amplification test [NAAT] within 2 months; n = 23) and those in the recovery phase from COVID-19 (negative on a SARS-CoV-2 NAAT for >2 months; n = 13). Results: The cytology diagnoses were negative for malignancy (n = 31), atypical (n = 4), and suspicious for malignancy (n = 1). Active infection cases showed more atypical mesothelial cells than recovery cases (P