The value of labial biopsy in the differentiation of sarcoidosis from tuberculosis.
BACKGROUND: Since the clinical features of sarcoidosis and tuberculosis may mimic each other, and that differentiation is not easy on clinical grounds, a histologic diagnosis may be mandatory in countries where the prevalence of tuberculosis is high or in populations with large numbers of immigrants from those countries. Previous studies have suggested the minor salivary gland biopsy as a useful method in the diagnosis of sarcoidosis. The present study was undertaken to evaluate the value of labial biopsy in the differentiation of sarcoidosis from tuberculosis in patients with enlarged hilar and paratracheal lymph nodes. METHODS: Labial biopsy was performed in 50 consecutive patients with sarcoidosis, and in 35 consecutive patients with tuberculosis who had intrathoracic lympadenopathy. The files of all patients were reviewed for the clinical presentation, radiographic features, SACE levels, tuberculin skin test anergy, and the frequency of positive labial biopsy in each disease. RESULTS: Noncaseating granulomas were present in labial biopsies obtained from 24 patients (48%) of 50 patients with sarcoidosis. Labial biopsies were positive in 4 of 6 patients who had an abnormality on eye examination and in 3 of 5 patients who had noncaseating granulomas on biopsy material from skin. In two of 4 patients who underwent mediastinoscopy, noncaseating granulomas were detected on labial biopsy. In contrast to the patients with sarcoidosis labial biopsies revealed normal minor salivary glands in all patients with tuberculosis. CONCLUSIONS: Labial biopsy has a high discriminatory value as a diagnostic tool in the differentiation of sarcoidosis from tuberculosis. Although it has a rather lower diagnostic yield than transbronchial lung biopsy, labial biopsy should be considered as a first line approach prior to performing other more invasive procedures for the tissue confirmation of sarcoidosis.