A new diagnosis of monoclonal B‐cell lymphocytosis with cytoplasmic inclusions in a patient with COVID‐19

Abstract

This chapter features a case study of a 75-year-old man, who is presented to the emergency department with fever and tachycardia. A diagnosis of corona virus disease 2019 (COVID-19) was made. A computed tomography scan of the chest showed bilateral interstitial infiltrates associated with multiple enlarged mediastinal lymph nodes. Two months later the WBC and lymphocyte count had returned to normal and repeated immunophenotyping showed only 0.63 × 10 9 /l CD5+ clonal B cells. However, lymphocytes with cytoplasmic crystals were still present. A diagnosis of monoclonal B-cell lymphocytosis (MBCL) was made. Patients with chronic lymphocytic leukemia (CLL) in whom COVID-19 led to a marked but transient increase in the lymphocyte count have been reported. In this case, COVID-19 in a patient with MBCL led to an increase in the lymphocyte count to a level simulating CLL, with follow-up indicating the correct diagnosis.