Clinical-radiological features and diagnostic modalities for mediastinal melioidosis.

Melioidosis is a potentially life-threatening infection caused by the Gram-negative bacillus Burkholderia pseudomallei. Mediastinal melioidosis has a range of clinical presentations, making it difficult to diagnose: we therefore reviewed the evidence on the clinical characteristics, radiological features and invasive diagnostic modalities or interventions. An electronic search was conducted on three databases (PubMed, SCOPUS, Google Scholar) from November to December 2022. The initial search yielded 120 results, of which 34 studies met the inclusion criteria, but only 31 full-texts were retrievable. Among these, 4 were cohort studies, 26 case reports or series and 1 a conference abstract. The four main themes covered were mediastinal melioidosis as a diagnostic dilemma, unexpected complications, invasive interventions or an accompanying thoracic feature. Radiological manifestations included matting, necrosis and abscess-like collection. Severe presentations of mediastinal melioidosis included superior vena cava obstruction, sinus tract formation and pericardial tamponade. Transbronchial needle aspiration was the most common invasive diagnostic modality. Further research is needed to understand the relationship between the thoracic features of melioidosis on patient prognosis, its relationship to melioidosis transmission and potential preventive measures.

Pleural fluid residue as a diagnostic tool for cytology-negative malignant pleural effusion: A proof-of-concept study.

Background: Pleural fluid residue, or macroscopic tissue, circulating freely in the pleural fluid obtained through direct filtration, may carry diagnostic histopathological information. We aimed to determine the histopathological concordance of pleural fluid residue in diagnosing TPE and MPE, compared with conventional pleural biopsy. This was a prospective cohort study of consecutive inpatients with cytology-negative exudative effusion who underwent pleuroscopy and had their initial suctioned pleural fluid filtered for residue samples. Pleural fluid residue demonstrated malignant cells in four out of seven cases of pleural biopsy-confirmed malignancy. Pleural fluid residue has comparable cytomorphology but reduced cellularity compared with pleural biopsy. No tuberculous histological features were present in the pleural fluid residue samples. In this preliminary study pleural fluid residue provided histopathological information for malignant pleural effusion, but no incremental diagnostic information for tuberculous effusion. However larger and more definitive studies are required to clarify these findings, and to explore the utility and suitability of pleural fluid residue for mutational analysis. What the study adds: This study demonstrates the potential of pleural fluid residue as a non-invasive diagnostic method for confirming malignancy in cytology-negative exudative effusion. What are the implications of the findings: In resource-limited settings or patients contraindicated for pleural biopsy, pleural fluid residue may provide a viable diagnostic alternative; however, this observation needs further validation.

The great masquerade: Empyema thoracis as an unusual presentation of primary lung malignancy.

Primary lung malignancy presenting as empyema is rare, with a reported incidence of 0.3%. We report a case of a 60- year-old man presenting with unilateral pleural effusion; diagnostic thoracocentesis confirmed Salmonella empyema. Post-drainage, chest radiograph showed persisting right hemithorax opacity; subsequent computed tomography revealed a right lung mass with right upper lobe bronchus obliteration. Percutaneous biopsy confirmed advanced stage lung adenocarcinoma. We discuss the mechanism of post-obstructive pneumonia in lung cancerassociated empyema and the utility of bedside ultrasound in diagnosis of lung masses. Clinicians are alerted to the possibility of lung malignancy in elderly patients presenting with empyema.