Patients with “atypical lymphocytes”

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By RobertBass

Patients with atypical lymphocytes found in their peripheral blood

In December 2019, the outbreak of coronavirus infection 2019 (COVID-19), in Wuhan, China quickly became a pandemic throughout the globe, including the USA. We began receiving peripheral blood smear reviews for COVID-19 patients in March 2020. We reviewed 15 peripheral blood samples from 15 patients who were admitted with COVID-19 atypical lymphocytes. These patients were between 26 and cat pillows 90 years old and included seven males and seven women. There were nine cases of peripheral blood smear consultations. These patients were concerned primarily about haemolysis, which was the most common cause. The next three cases involved anaemia and thrombocytopenia.

The Existence of Atypical Lymphocytes

The majority of patients had normocytic and mild anisopoikilocytosis. No case was found to have morphological evidence that they had haemolysis regardless of clinical presentation. Two patients suffered from neutrophilia while two others had neutropenia. Six patients’ neutrophil counts were normal. Eight patients had a lymphocyte count lower than normal (normal range 1*0-4*0 K/ml), and seven suffered from lymphopenia. These findings were not the only ones that were observed. The most frequent observation was the existence of atypical lymphocytes, which was found in most smears (14/15 and 93*3%). These lymphocytes range in size from medium to large with condensed chromatin and deep basophilic cells (Fig 1A). Some cells have plasmacytoid morphology, with perinuclear hof and eccentric nuclei Fig 1B. Some cells have visible nucleoli that resemble immunoblasts Fig. 1C. Atypical lymphocytes made up 6*94 +-4*30% of total lymphocytes (Fig 1D). The percentage of atypically shaped lymphocytes in total lymphocytes was not related to severity of disease, as shown in Fig 1D.

These unusual lymphocytes

These unusual lymphocytes may be reactive to severe acute respiratory syndrome coronavirus 2 infection (SARS-CoV-2). They have a different morphology than Downey type 2 reactive lymphocytes (Fig 1F) that are often seen in viral infections like Epstein-Barr virus. Our 15 patients reviewed had Downey type II reactive atypical lymphocytes. However, they were not seen at a higher frequency (0*50 + 0*85%) Lymphopenia, which is common in SARS and influenza, has been recognized as a negative predictor for outcomes. 1, 2. Atypical lymphocytes are not an indicator of influenza. These cells are more common than other viral infections and may be a clue in determining if patients should be evaluated for COVID-19. Future research on the characterisation and function of these cells may help us understand the pathophysiology.

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