Can cytomorphology of granulomas distinguish sarcoidosis from tuberculosis? Retrospective study of endobronchial ultrasound guided transbronchial needle aspirate of 49 granulomatous lymph nodes

BACKGROUND: The differential diagnosis of tuberculosis (TB) and sarcoidosis on fine needle aspiration material is very challenging in tubercular endemic regions. We carried out a pilot study to explore cytomorphologic features of granulomas which could help in differentiation between sarcoidosis and TB. Final diagnoses in these patients were based on clinical, microbiologic and follow-up studies. MATERIALS AND METHODS: Endobronchial ultrasound guided transbronchial needle aspiration smears of 49 consecutive patients with a final cytologic diagnosis of granulomatous lymphadenitis were reviewed. Based on cytologic features two cytologic categories were enunciated and the results were correlated with microbiologic studies and/follow-up of minimum of 6 months. RESULTS: The cytologic categories did not correlate with the final clinical outcome of patients. CONCLUSIONS: Different patterns of granulomas observed in cytology smears do not help distinguish TB from sarcoidosis. The novel non-invasive techniques of mediastinal sampling though help in confirming granulomatous pathology, distinction between these entities and treatment decisions still depend upon correlating cytologic, microbiologic, clinical and radiological data in a large number of cases in tubercular endemic regions.