Leukemoid reaction: Case report

A Predictive Algorithm for Discriminating Myeloid Malignancies and Leukemoid Reactions

BACKGROUND

Adults presenting with a neutrophil-predominant leukocytosis (white cell count >50,000/μL) often necessitate urgent medical management. These patients are diagnosed with either acute presentations of chronic myeloid malignancies or leukemoid reactions, yet accurate models to distinguish between these entities do not exist. We used demographic and lab data to build a machine learning model capable of discriminating between these diagnoses.

METHODS

The medical record at a tertiary care medical center was queried to identify adults with instances of white counts greater than 50,000/μL and >50% neutrophils from 2000 to 2021. For each patient, a full set of demographic and lab values were extracted at the time of their first presentation with a white count >50,000/μL. We generated a series of models in which the parameters most predictive of myeloid malignancies were identified, and a supervised machine learning approach was applied to the dataset.

RESULTS

Our best model-using a support vector machine algorithm-produced a sensitivity of 96% and a specificity of 95.9% (area under the curve = 0.982) for identifying myeloid malignancies. We also identified a clinically meaningful and significant disparity in outcomes based on diagnosis-a 6-fold increase in 12-month mortality in those diagnosed with leukemoid reactions.

CONCLUSIONS

These findings need to be validated but fill an unmet need for timely and accurate diagnosis in the setting of profound, neutrophil-predominant leukocytosis and support the use of predictive models as a means to improve patient outcomes.

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.