Morphologic Changes in Circulating Blood Cells of COVID-19 Patients.

Objective Since the beginning of the coronavirus disease 2019 (COVID-19) pandemic, many studies have described the quantitative peripheral blood findings seen in COVID-19 patients. However, morphologic changes have been described by only a few studies. We report morphologic and quantitative changes in peripheral blood of COVID-19 patients. Design We reviewed electronic medical records, complete blood counts, and peripheral blood smears of 20 patients who were COVID-19 positive by reverse transcriptase-polymerase chain reaction (RT-PCR), from March 1, 2020, through May 31, 2020. The peripheral blood smears of all 20 patients were retrieved and morphological features of white blood cells, red blood cells, and platelets were reviewed and documented. Appropriate pictures were taken. Results Of the 20 patients reviewed, 13 were males and seven were females. The average age of the patients was 65.1 years. The most common quantitative hematologic abnormalities noted on complete blood count (CBC) were anemia followed by neutrophilia, neutrophilic left shift, and lymphopenia. The most significant morphologic changes noted were neutrophils with clumped chromatin, multiple abnormal nuclear shapes, pseudo-Pelger-Huet deformity, and smudged neutrophils. Lymphocytes showed abundant blue cytoplasm and/or lymphoplasmacytoid morphology and monocytes were activated with abnormal shapes and vacuolization. Platelets were adequate in number in the majority of patients and platelet clumping was the most significant finding noted. The red blood cells were normocytic and normochromic with few nucleated red blood cells and coarse basophilic stippling. Conclusion Our study identifies and describes significant morphologic changes in the peripheral blood cells of COVID-19 patients. An understanding of these morphologic changes in addition to established hematologic parameters can aid in the diagnosis of COVID-19 and serial CBC and peripheral smear review may help with management decisions in COVID-19 patients.