Leukemoid Reaction in a Patient With Severe COVID-19 Infection.

Leukemoid reaction is a rare clinical condition defined by marked leukocytosis with predominantly mature neutrophils. It is an uncommon condition with reported incidence of less than 1% in hospitalized patients. The major causes of leukemoid reaction are severe infection (clostridium difficile colitis, tuberculosis, or severe shigellosis), malignancies, intoxication, and severe hemorrhage. This article presents a case report of a 64-year-old female with severe COVID-19 infection who presented with marked leukocytosis. After extensive workup to exclude hematologic malignancy, the patient was diagnosed to have a leukemoid reaction.