Mediastinal granulomatous lymphadenitis in a population at risk for HIV and tuberculosis.

Background: Granulomatous inflammation on transbronchial needle aspirates from mediastinal lymph nodes is an infrequent yet important finding. We determined associations between cytomorphological features and underlying aetiology in an area of high prevalence of HIV-infection and tuberculosis.

Methods: We identified cases with granulomatous inflammation on mediastinal aspirates from January 2003 to July 2010. Cytomorphological features were evaluated and graded according to a simple and reproducible system including the presence, quality (discrete or vague), and number (≤5 or more) of granulomas as well as the presence of necrosis, lymphocytes, multinucleated giant cells, and neutrophils.

Results: In 81 patients (36 male, 9 HIV-positive) the final diagnosis was tuberculosis in 37 (46%), sarcoidosis in 40 (49%), fibrosing mediastinitis in 1 (1%), and unknown in 3 (4%). The presence of necrosis (P < 0.001) and neutrophils (P = 0.05) was associated with tuberculosis and numerous discrete granulomas were associated with sarcoidosis (P = 0.03). All HIV-positive patients were diagnosed with tuberculosis.

Conclusion: Granulomatous disease identified on TBNA from mediastinal lymph nodes is mostly associated with sarcoidosis and tuberculosis. Ancillary investigations for sarcoidosis are appropriate if numerous discrete granulomas are found. Tuberculosis must be excluded if necrosis and neutrophils are present and in HIV-positive individuals, particularly in high-burden areas of tuberculosis.