PO33 - Prevalence of granulomatous inflammation in the lungs in subjects with intrathoracic lymphadenopathy due to sarcoidosis and tuberculosis: Is there a difference?
Sahajal Dhooria (India)1; Kuruswamy Thurai Prasad (Portugal)1; Ritesh Agarwal (India)1; Nalini Gupta (India)2; Amanjit Bal (India)3; Ashutosh Nath Aggarwal (India)1;
1 - Department of Pulmonary Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh; 2 - Department of Cytology and Gynecologic Pathology, Postgraduate Institute of Medical Education and Research, Chandigarh; 3 - Department of Histopathology, Postgraduate Institute of Medical Education and Research, Chandigarh;
Keywords: sarcoidosis; tuberculosis; lung biopsy;
Select the theme: Challenges in Sarcoidosis Diagnosis and Staging
Type: Original Papers
Presentation: Poster Presentation

Introduction: In subjects with intrathoracic lymphadenopathy due to sarcoidosis and tuberculosis (TB), differentiating one disorder from the other is challenging. In sarcoidosis, lung biopsy may yield granulomas, even from radiologically normal lung parenchyma (RNLP) and endoscopically normal-appearing bronchial mucosa (ENBM). Whether the same is true for TB remains unknown.

Objectives: (1) To compare the prevalence of granulomatous inflammation (GI) on TBLB (primary).

(2) To evaluate whether the presence of GI from RNLP or ENBM is associated with sarcoidosis (key secondary).

Materials and Methods: We prospectively screened subjects with intrathoracic lymphadenopathy suspected to be due to sarcoidosis or TB. Subjects who underwent transbronchial lung biopsy (TBLB) along with other bronchoscopic sampling procedures and had a final diagnosis of sarcoidosis or TB were included. We compared the primary outcome between sarcoidosis and TB with the chi-square test. We also performed a multivariable logistic regression analysis to assess factors associated with the diagnosis of sarcoidosis.

Results: We screened 170 subjects, of whom 114 subjects (sarcoidosis, n=76; TB, n=38) underwent TBLB. GI in TBLB was more common in sarcoidosis than TB (55.3% vs. 21.1%, p=0.001). Sixty-one (53.5%) and 108 (94.7%) subjects had RNLP and ENBM, respectively. In those with RNLP, we found GI more commonly in sarcoidosis than TB (52.8% vs. 12.0%, p=0.001), while this difference was not observed for ENBM. In subjects with both RNLP and ENBM, granulomas were more frequently detected in sarcoidosis than TB (58.8% vs. 12.0%, p<0.001), in specimens from either biopsy procedure (TBLB or EBB). On multivariable logistic regression, GI from RNLP or ENBM did not independently predict sarcoidosis beyond tuberculin sensitivity (adjusted odds ratio [aOR], 0.01; p<0.001) and body mass index (aOR, 1.19; p=0.03).

Conclusions: Granulomatous inflammation in radiologically normal lung parenchyma is more frequent in sarcoidosis than tuberculosis, but should be interpreted alongside clinical and immunological parameters. Further studies are needed to validate our findings.