Smear Negative Pulmonary Tuberculosis Is a Distinct Clinical Entity, Not a "Misdiagnosis Waste Basket"

Abstract

Background: PTB can mimic many chronic lung diseases resulting in misdiagnosis with serious consequences. Objectives: To appraise all SN PTB patients who were referred to us from lower health facilities after unsuccessful treatment in order to confirm the appropriate diagnosis. Methods: A cross sectional study at the pulmonary section of our hospital. Results: The median age of our patients was 46 with interquartile range of 32 to 54 years. The commonest presenting symptom was difficulty in breathing which was present in almost 90% of them (30 out of 34), cough was present in 24 with sputum production in 22 while haemoptysis was reported in 3. All the 5 patients with malignancy reported chest pain. Sixty eight percent of the patients were referred from Peripheral TB DOT centers and sputum smear tests were done in 82% of them while radiologic tests were done in less than 50% of the patients. The final diagnoses include COPD, malignancy, sarcoidosis, interstitial lung diseases and fungal infection among others. Conclusion: Many lung diseases are misdiagnosed as SN PTB because of similarity in clinical presentation, overreliance on diagnostic test with low TB detection and non adherence to local guidelines. We advocate for WHO-recommended rapid molecular test for all our suspected TB cases and prompt referral of difficult to diagnose cases.