Atypical presentation of Legionella pneumonia among patients with underlying cancer: A fifteen-year review

•Legionella infection can present as nodular lung lesions in immunocompromised patients.•Radiographic presentation of Legionella mimics invasive fungal infection.•Nodular disease is mostly caused by infection with non-pneumophila species.•Atypical pulmonary nodule(s) due to Legionella cause a clinically mild illness.

SummaryBackgroundImmunocompromised patients, especially those receiving treatment with corticosteroids and cytotoxic chemotherapy are at increased risk for developing Legionella pneumonia.ObjectiveThe aim of this study was to determine clinical and radiographic characteristics of pulmonary infection due to Legionella in persons undergoing treatment for cancer and stem cell transplant (SCT) recipients.MethodsRetrospective review of Legionella cases at MSKCC over a fifteen-year study period from January 1999 and December 2013. Cases were identified by review of microbiology records.ResultsDuring the study period, 40 cases of Legionella infection were identified; nine among these were due to non-pneumophila species. Most cases occurred during the summer. The majority [8/9, (89%)] of patients with non-pneumophila infection had underlying hematologic malignancy, compared to 18/31 (58%) with Legionella pneumophila infections. Radiographic findings were varied-nodular infiltrates mimicking invasive fungal infection were seen only among patients with hematologic malignancy and hematopoietic stem cell transplant (SCT) recipients and were frequently associated with non-pneumophila infections (50% vs 16%; P = 0.0594). All cases of nodular Legionella pneumonia were found incidentally or had an indolent clinical course.ConclusionsLegionella should be considered in the differential diagnosis of nodular lung lesions in immunocompromised patients, especially those with hematologic malignancy and SCT recipients. Most cases of nodular disease due to Legionella are associated with non-pneumophila infections.