TB PLEURAL EFFUSION: AN ANOMALOUS DIAGNOSIS

Abstract

SESSION TITLE: Monday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/21/2019 02:30 PM - 03:15 PM INTRODUCTION: Tuberculous pleural effusions (TPE) are a common manifestation of extrapulmonary tuberculosis. A diagnostic approach includes pleural fluid analysis, acid-fast stain and culture, and pleural biopsy. Our case demonstrates a patient with a tuberculous pleural effusion whose pleural fluid analysis was inconsistent with standard diagnostic parameters and whose diagnosis of Mycobacterium tuberculosis was ultimately confirmed by pleural fluid culture, not tissue stain or culture. CASE PRESENTATION: A 44-year old HIV-negative female originally from Ecuador who immigrated 5 months prior presented to our hospital with persistent right chest pain gradually worsening over the past several weeks. She reported unintentional weight loss and occasional night sweats. Sputum was negative for acid fast bacilli. CT chest demonstrated a large right pleural effusion and 1.75L of fluid was drained. Analysis revealed an exudative effusion with an alkalotic pH of 7.7, nucleated cell count of 219 u/L with 61% lymphocytes, with stain and preliminary cultures negative. Adenosine deaminase (ADA) was measured to be 5.0 U/L. The patient had quick recurrence of the effusion after thoracentesis and since the diagnosis was not clear, thoracoscopy and pleural biopsy were performed. The histopathology showed necrotizing granulomas without evidence of acid-fast bacilli. Because of the high suspicion, the patient was treated for tuberculosis. After four weeks, the original pleural fluid drained grew M. tuberculosis. DISCUSSION: Our case is interesting because despite inconsistent pleural fluid findings, M. tuberculosis ultimately grew from pleural fluid cultures. In general, pleural fluid cultures are positive in fewer than 20 to 30 percent of HIV-uninfected patients and are much lower yield than pleural biopsy. Typically pleural fluid displays a pH <7.4 and this is rarely ever greater than 7.4 in TPE. Nucleated cell counts are usually between 1000-5000 u/L. It is accepted that in areas with high tuberculosis prevalence, the easiest way to establish the diagnosis of TPE in a patient with a lymphocytic pleural effusion is with an adenosine deaminase level above 40 U/L. Many studies suggest a very high negative predictive value of ADA, with an ADA level <40 virtually excluding the diagnosis of a TPE. Certainly false-negatives can still occur with ADA and there are studies to show that preservation methods can influence its degradation as well. However, given the findings of a high pH and low nucleated cell count, making a diagnosis of a TPE was unquestionably complicated. CONCLUSIONS: In conclusion, it is unusual to have these pleural fluid findings as well as a non-diagnostic pleural biopsy in a patient who eventually had confirmed TPE from the pleural fluid culture. Reference #1: Kataria, Yash, et al. Adenosine Deaminase in the Diagnosis of Tuberculous Pleural Effusion. Chest Journal. 2001; 120 (2); 334-36 Reference #2: Vorster, Morne, et al , Tuberculous pleural effusions: advances and controversies. Journal of Thoracic Disease. 2015; 7 (6); 981-91 Reference #3: Zai, Kan et al. Tuberculous Pleural Effusion. Journal of Thoracic Disease. 2016 Jul; 8(7): E486–E494 DISCLOSURES: No relevant relationships by Walter Chua, source=Web Response No relevant relationships by Sara Huda, source=Web Response No relevant relationships by Jessica Norsworthy, source=Web Response No relevant relationships by Gulru Sharifova, source=Web Response