Factors Determining Successful Diagnostic Yield of Conventional Transbronchial Needle Aspiration in the Diagnosis of Sarcoidosis

To the Editor: Sarcoidosis is a multisystem granulomatous disorder of unknown etiology usually manifesting with constitutional symptoms and mediastinal lymphadenopathy, with or without pulmonary parenchymal abnormalities.1 The diagnosis is made on a combination of compatible clinical and radiologic presentation with histologic demonstration of noncaseating granuloma, usually from enlarged intrathoracic lymph node.2 The sampling of mediastinal/hilar lymph node requires the performance of either conventional transbronchial needle aspiration (cTBNA) or endobronchial ultrasound (EBUS)-guided TBNA. Of the 2, EBUS-TBNA has a higher yield compared with cTBNA.3 However, the access or expertise for performing EBUS-TBNA may not be available at all centers, especially in the developing countries. Recently, we have demonstrated that the diagnostic yield of conventional bronchoscopy [cTBNA plus endobronchial biopsy (EBB) and transbronchial lung biopsy (TBLB)] is similar to EBUSTBNA plus TBLB.4 The diagnostic yield of cTBNA can be further improved if one is aware of the factors associated with a successful procedure. In the current study, we aimed to identify the factors that may predict the successful diagnostic yield of cTBNA in sarcoidosis. This was a retrospective analysis of data of patients with sarcoidosis who underwent cTBNA between January 2011 and May 2015. The study was approved by the Ethics Review Committee, and a written informed consent was obtained from all the subjects. Conventional bronchoscopy including cTBNA, EBB, and TBLB was performed, as previously described.5 Rapid onsite evaluation (ROSE) on the cytologic material aspirated by cTBNA was not available. A successful diagnostic yield on cTBNA was considered if the aspirates yielded non-necrotizing granulomas or collection of epitheloid cells with giant cells or Schaumann or asteroid bodies. A diagnosis of sarcoidosis was made on the basis of the presence of consistent clinical and radiologic presentation along with demonstration of non-necrotizing granulomas along with negative acid-fast bacilli and fungal stains. A final diagnosis of sarcoidosis was made at 6 months after clinical and radiologic response to treatment with glucocorticoids. A total of 210 cTBNA procedures were performed for various indications during the study period. Sarcoidosis (stage I and stage II) was diagnosed in 114 (54.3%) patients who underwent cTBNA. The mean (SD) age of patients (50.9% females) was 41.3 (11.3) years (Table 1). Tuberculin skin test was positive in 5 (4.4%) patients. A total of 215 (station 4R, n=113; station 7, n=102) lymph nodes were sampled, and a minimum of 2 to 3 passes were taken from each lymph node station. The median (interquartile range) time taken to perform cTBNA with EBB and TBLB was 15 (15 to 20) minutes. One patient each had transient hypoxemia and minor bleeding that did not require any intervention. A successful diagnosis of sarcoidosis on cTBNA alone was made in 70 (61.4%) patients, whereas in 44 (38.6%) patients the diagnosis was made either on EBB, TBLB, or both. Of the 44 unsuccessful cTBNA, lymphocytes were seen in 35 samples, and in 9 patients, the sample was not representative. The age, sex, lymph node size on computed tomography of the chest, and the number of passes are shown in Table 2. We did not identify any factor that predicted a successful diagnostic yield in sarcoidosis with cTBNA (Table 2). Our study highlights that cTBNA helps in making a diagnosis of sarcoidosis in about 60% of the cases, which is very close to the figure reported in a recent meta-analysis.6 Unfortunately, we were unable to identify any factor that predicted successful sampling of mediastinal lymph nodes in confirming sarcoidosis. In another study involving 57 patients with sarcoidosis, cTBNA identified non-necrotizing granulomas in 63% of the nodes sampled; this study also did not identify factor predicting the successful yield of cTBNA in the diagnosis of sarcoidosis. However, in 1 study of Disclosure: There is no conflict of interest or other disclosures.