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.

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.

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