# Cold Agglutinin-Mediated Hemolysis as an Extrapulmonary Manifestation of Mycoplasma pneumoniae Infection: A Case Report

## TL;DR

A young man with a Mycoplasma pneumoniae infection developed anemia due to cold agglutinin-mediated hemolysis, highlighting a rare but important extrapulmonary complication.

## Contribution

This case report highlights cold agglutinin-mediated hemolysis as a rare extrapulmonary manifestation of Mycoplasma pneumoniae infection.

## Key findings

- A 20-year-old man with Mycoplasma pneumoniae infection developed cold agglutinin-mediated hemolysis.
- Targeted azithromycin therapy led to clinical and hematologic improvement.
- The case underscores the importance of recognizing non-respiratory complications of M. pneumoniae infections.

## Abstract

Mycoplasma pneumoniae (M. pneumoniae) is a frequent cause of community-acquired pneumonia (CAP) in young adults and may present with extrapulmonary manifestations, including hematologic complications such as cold agglutinin-mediated hemolysis. We report the case of a previously healthy 20-year-old Caucasian man who presented with a four-day history of fever, asthenia, anorexia, and dry cough. Imaging revealed extensive left-sided pulmonary consolidation, and empirical therapy for CAP was initiated. During hospitalization, new-onset anemia with erythrocyte agglutination following blood warming raised suspicion of immune-mediated hemolysis, later supported by positive cold agglutinins and serologic confirmation of M. pneumoniae infection. The patient showed progressive clinical and analytical improvement with targeted azithromycin therapy. He remained asymptomatic and hematologically stable at the three-month follow-up. This case reinforces the importance of recognizing significant hematologic manifestations that may accompany or even precede respiratory involvement in M. pneumoniae infections. Early identification of cold agglutinin-associated hemolysis can expedite diagnostic evaluation and guide appropriate therapy, contributing to favorable outcomes.