# A Twist in the Tale: An Unexpected Pathogen in a Patient With a Cavitary Lung Lesion

## TL;DR

A rare Legionella infection in a patient with a lung lesion was complicated by a false test result, emphasizing the need for careful diagnosis in immunocompromised individuals.

## Contribution

Highlights the diagnostic challenges of atypical pathogens in immunocompromised patients and the importance of multidisciplinary care.

## Key findings

- A false-positive galactomannan test led to unnecessary treatment in a patient with Legionella lung abscess.
- Surgical resection and targeted antibiotic therapy were critical for managing the infection.
- The case underscores the importance of accurate lab interpretation in immunocompromised patients.

## Abstract

We present a challenging case of Legionella pneumophila lung abscess in a 58-year-old woman with myelodysplastic syndrome presenting with a cavitary lung lesion. The diagnostic workup was complicated by a false-positive galactomannan result, resulting in unnecessary medicamentous treatment and possible different therapeutic decisions. Management involved surgical resection regarding a necessary stem cell transplant and prolonged antibiotic (with monotherapy versus broad-spectrum) and antifungal therapy. This case highlights the need to consider atypical pathogens in immunocompromised patients, even when other findings suggest more common infections, and underscores the importance of a multidisciplinary approach and careful interpretation of laboratory results to guide appropriate management strategies.