Sarcoidal Granulomas in Cytological Specimens from Intrathoracic Adenopathy: Morphologic Characteristics and Radiographic Correlations

Abstract

Background: Clinical experience and literature data suggest that the ability of pathologists to identify granulomas in cytological specimens from intrathoracic lymphadenopathy varies considerably and may negatively influence the yield of transbronchial needle aspiration (TBNA), both conventional and ultrasound-guided (EBUS-TBNA). Objectives: To describe the cytomorphology of sarcoidal granulomas on TBNA cytology specimens and to analyze the presence of associations between the cytological characteristics of granulomas and the radiographic stage of sarcoidosis. Methods: TBNA cytological specimens from 123 sarcoidosis patients and 14 tuberculosis patients (control population) were reviewed independently by two pathologists blinded to the clinical-radiological details. Results: Sarcoidal granulomas were small [median (IQR) largest diameter: 0.478 (0.318-0.701) mm] and well-formed, round or elliptical in shape, and almost invariably had a regular contour. Background elements lacked necrotic debris or exudate. The density [median (IQR) number of granulomas per slide: 6.85 (3.66-11) vs. 5.25 (2.5-8), p = 0.073] and size [median (IQR) largest diameter: 0.51 (0.319-0.733) vs. 0.398 (0.318-0.522), p = 0.071] tended to be larger in stage I than in stage II sarcoidosis. A necrotic background was common in the tuberculosis cohort studied (79 vs. 0%, p < 0.0001). Conclusions: Granulomas can be reliably identified on TBNA cytological material once their characteristic cytomorphology is delineated. A higher density of granulomas in lymphadenopathy of stage I sarcoidosis patients could partly explain the higher success rate constantly obtained by TBNA and EBUS-TBNA in this stage of the disease. A necrotic background suggests a tubercular etiology of the granulomas over a sarcoidal one, in the appropriate clinical setting.