The Silent Sentinel's Breach: Middle Lobe Syndrome Caused by Endobronchial Rupture of Mediastinal Tuberculous Lymphadenitis.

Middle lobe syndrome (MLS) is characterized by recurrent or chronic collapse of the right middle lobe of the lung. While non-vascular inflammatory causes dominate, endobronchial rupture of mediastinal tuberculous lymphadenitis causing obstructive MLS is an under-recognized entity that presents significant diagnostic challenges. In this context, we report the case of a 24-year-old male immigrant with no past medical history who presented with cough and right-sided chest pain. Chest radiography revealed right middle lobe alveolar opacity. He received empirical levofloxacin without radiological follow-up. Four months later, he experienced symptom recurrence associated with weight loss, asthenia, and night sweats. Repeat chest radiography revealed persistent middle lobe consolidation with ipsilateral pleural effusion. Sputum smear for acid-fast bacilli and PCR for Mycobacterium tuberculosis were negative. Chest CT confirmed necrotic mediastinal lymph nodes with endobronchial rupture into the middle lobe bronchus and cavitated middle lobe consolidation. Flexible bronchoscopy demonstrated mucosal infiltration and pearly-white stenosis of the middle lobar bronchus. Endobronchial biopsies revealed necrotizing epithelioid and giant-cell granulomatous inflammation. The diagnosis of obstructive MLS secondary to endobronchial tuberculosis following lymph node rupture was established, and antituberculosis therapy was initiated. In conclusion, tuberculous lymphadenitis with broncho-nodular fistulization should be considered in the etiology of obstructive MLS. Initial empirical fluoroquinolone treatment can mask bacteriological detection, highlighting the essential diagnostic role of endobronchial biopsies.