Conference Abstract: A Rare Case of Pleural Non Tuberculous Mycobacterial Infection in the Absence of Pulmonary Infection

Published Date: 01st May 2025

Publication Authors: Langley. K, Badawi. A, Evans. C

Introduction
To our knowledge, there are only four previously published case reports of pleural mycobacterium xenopi (m.xenopi) infection, and only one in the absence of co-existent pulmonary infection. We describe a case of a 78-year-old male previously treated with rituximab for small lymphocytic lymphoma who had slowly progressing unilateral pleural thickening, which was found to be caused by m.xenopi. In this case, we suspect that the immunomodulatory effects of rituximab predisposed the patient to this extremely rare infection.

Description
A 78-year-old male was referred to the respiratory team at Whiston Hospital in North-west England due to a radiological finding of left pleural thickening. The patient had a background of small lymphocytic lymphoma, for which he had received rituximab in 2015, as well as mild chronic obstructive pulmonary disease and radiological bibasal bronchiectasis, without the clinical syndrome. He presented to the emergency department in January 2024 with atypical chest and abdominal pain and underwent a computed tomography (CT) scan of his aorta to exclude dissection, before later being diagnosed with a urinary tract infection and discharged following antibiotic treatment. On retrospective imaging review, the finding appeared to be slowly progressing, with identifiable minor thickening dating back to 2014. Following review by a thoracic radiologist, the finding was described as "focal pleural thickening peripherally at the left base, which bulges into the extra-pleural fat," and "slightly atypical, but appears well defined with no rib destruction." The patient was assessed in respiratory clinic and reported chronic mild breathlessness and a morning cough, but had no significant weight loss, fevers, or sweats. He had previously worked as a joiner and denied asbestos exposure. Positron emission tomography-CT was performed with mild-to-moderate fluorodeoxyglucose avidity. Subsequent CT-guided pleural biopsy histology revealed granulomatous inflammation, and purulent material was sent for bacterial and mycobacterial culture. Acid-fast bacilli were identified on Ziehl-Neelsen staining and the subsequent culture revealed m.xenopi, with cytology re. There was no radiological or clinical evidence of co-existing pulmonary non-tuberculous mycobacterial (NTM) infection.

Discussion
Use of immunomodulatory drugs and monoclonal antibodies is widespread across oncology and rheumatology, and some drugs may cause long-lasting immune dysfunction. This case of a patient with previous exposure to rituximab demonstrates the need to consider and investigate for rare pathogens when the clinical presentation or radiological findings are atypical, and when a patient has been treated with prior immunomodulating therapies.

Langley, K; Badawi, A; Evans, C. (2025). Conference Abstract: A Rare Case of Pleural Non Tuberculous Mycobacterial Infection in the Absence of Pulmonary Infection. American Journal of Respiratory and Critical Care Medicine. 211(Conference Abstracts), p.A6619. [Online]. Available at: https://doi.org/10.1164/ajrccm.2025.211.Abstracts.A6619 [Accessed 17 July 2025]

 

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