A comparison of the clinical profile of Sarcoidosis and Mediastinal TB: A prospective cohort study in a TB endemic population

<b>Introduction:</b> Differentiating Sarcoidosis from Mediastinal TB is challenging, especially in TB endemic settings. There is scant literature on the comparative clinical profile of patients with histologically confirmed Sarcoidosis and Mediastinal TB. <b>Aim:</b> To compare the clinical profile, diagnostic investigations, and pathological findings among patients with Sarcoidosis and Mediastinal TB. <b>Methods:</b> Ethical approval was obtained. We prospectively enrolled subjects with a diagnosis of Sarcoidosis and Mediastinal TB from the chest clinic at a tertiary care referral facility. Treatment response at six-months was considered as the gold standard for diagnosis. <b>Results:</b> Compared to Mediastinal TB (n=115), patients with Sarcoidosis (n=327) were younger, had a higher BMI, longer symptom duration (308 ± 27 vs. 114 ± 11 days) and higher prevalence of diabetes and hypothyroidism. Breathlessness and cough were more frequent, while fatigue and anorexia were more common in Mediastinal TB. Serum ACE levels, urine 24-hr calcium, and blood eosinophil count were higher in sarcoidosis. Significantly more subjects with Sarcoidosis were tuberculin anergic (71.9 % vs. 7.8 %). Necrotic lymph nodes and single nodal station involvement on CT were higher in mediastinal TB. On Endobronchial Ultrasound (EBUS), coagulation necrosis sign (26.2% vs. 2.3%) and heterogenous node appearance (51.4% vs. 4.9%) were more frequent in TB. On pathology, necrosis or necrotizing granulomas were more common in TB (55.6% vs. 13.5%) compared with Sarcoidosis. <b>Conclusion:</b> A comprehensive clinical, radiological and pathological approach may allow accurate differentiation of Sarcoidosis from Mediastinal TB.