Endobronchial Blood Clot as the Presenting Feature of Sputum-Negative Pulmonary Tuberculosis in a Young Adult: The Diagnostic Value of Bronchoscopic Tissue Sampling

Abstract

Background: Pulmonary tuberculosis (TB) remains the foremost infectious cause of mortality in sub-Saharan Africa, yet endobronchial tuberculosis (EBTB)—defined by mycobacterial invasion of the tracheobronchial mucosa—continues to be diagnostically elusive. Sputum smear microscopy, the most widely available TB diagnostic test in resource-limited settings, is frequently negative in EBTB due to paucibacillary mucosal disease, creating a critical diagnostic gap that non-invasive testing cannot bridge. Haemoptysis from EBTB-related mucosal erosion can culminate in an organised endobronchial blood clot—a rare but potentially life-threatening complication that simultaneously obstructs the airway and harbours the very mycobacterial material needed for diagnosis. This dual clinical and diagnostic significance is underappreciated in practice. To the best of our knowledge, we present the first reported case of this presentation from Kenya, managed through a structured multimodal bronchoscopic protocol, with complete WHO-defined treatment success and objective bilateral radiological resolution at six months. Case Presentation: A 21-year-old BCG-naive male (70 kg) presented to a tertiary referral hospital in Nairobi, Kenya, with a seven-day history of moderate haemoptysis (~100 mL per episode), drenching night sweats, fever, and progressive weight loss. Clinical examination revealed haemodynamic stability (HR 87 bpm, BP 120/80 mmHg, SpO 2 99% on room air) with absent right lung breath sounds, directly predictive of the complete right main bronchial obstruction confirmed bronchoscopically. Chest radiograph demonstrated bilateral pulmonary infiltrates with left-predominant consolidation. Contrast-enhanced CT revealed bilateral ground-glass opacities, right lower lobe consolidation, and a centrally cavitating left upper lobe nodule (12.2 mm) with adjacent calcific foci. Laboratory investigations demonstrated moderate anaemia (Hb 9.0 g/dL), mild thrombocytopenia (platelets 120 × 10 9 /L, a recognised manifestation of active TB), elevated CRP (55 mg/L), normal coagulation studies (APTT and INR), normal liver function tests, and normal baseline visual acuity (Snellen 6/6 bilaterally; Ishihara colour vision normal). HIV was confirmed negative by both ELISA and PCR. A BioFire FilmArray Respiratory Panel was comprehensively negative for all viral and atypical bacterial respiratory pathogens, systematically excluding alternative infectious aetiologies. Sputum AFB smear microscopy was negative. Flexible bronchoscopy under general anaesthesia (ETT 7.5 mm, 45-minute procedure) performed by Dr. Yashar Najiaghdam (Consultant Intensivist) identified complete right main bronchial obstruction by an organised blood clot, with diffuse mucosal erythema, petechial haemorrhage, and friability consistent with endobronchial TB throughout the tracheobronchial tree. The clot was extracted by high-flow suction, immediately restoring airway patency. BAL GeneXpert MTB/RIF confirmed Mycobacterium tuberculosis at Very Low level (Ct > 28; RIF-sensitive), directly explaining smear negativity through paucibacillary burden. Ziehl-Neelsen staining of the retrieved clot independently confirmed acid-fast bacilli, providing convergent dual-modality bacteriological and histopathological confirmation. Management and Outcome: Standard six-month DS-TB therapy was initiated within 48 hours of bronchoscopic confirmation: intensive phase 2HRZE—Isoniazid 300 mg, Rifampicin 600 mg, Pyrazinamide 1750 mg, Ethambutol 1,050 mg, Pyridoxine 25 mg once daily (weight-based per WHO 2022, 60 - 74 kg band)—followed by continuation phase 4HR. Directly Observed Therapy was arranged. Haemoptysis resolved immediately post-bronchoscopy and did not recur. Sputum conversion was confirmed at Month 2. The patient completed the full regimen without adverse drug reactions or interruption, and was declared a WHO-defined treatment success. Follow-up posteroanterior chest radiograph at six months demonstrated near-complete bilateral radiological resolution, with only mild residual reticular markings consistent with post-inflammatory fibrotic change. Discussion: Three clinically critical principles emerge from this case. First, a negative sputum smear must never constitute grounds for diagnostic closure in EBTB: paucibacillary mucosal disease produces bacillary burdens below smear detection thresholds, detectable only by sensitive molecular amplification, as confirmed by the Very Low GeneXpert result (Ct > 28) on BAL. Second, the organised endobronchial clot—a haemorrhagic complication requiring urgent extraction—simultaneously constitutes the most diagnostically informative specimen available, yielding AFB on ZN staining when all non-invasive methods have failed. Third, bronchoscopy under general anaesthesia with systematic BAL collection and submission of all retrieved material for GeneXpert and histopathology enables simultaneous therapeutic resolution and definitive diagnosis in a single procedure, a clinically efficient and lifesaving approach in resource-limited environments. Conclusion: This case establishes a clear, reproducible protocol for adolescent sputum-negative haemoptysis in TB-endemic sub-Saharan Africa. Negative sputum smear alongside a compatible clinical triad, characteristic CT findings, and systematic exclusion of alternative pathogens mandate bronchoscopy without delay. A structured approach—general anaesthesia with endotracheal intubation, clot extraction by high-flow suction, BAL for GeneXpert MTB/RIF, and ZN staining of all retrieved endobronchial material—delivers simultaneous airway clearance and bacteriological confirmation. When MTBC is confirmed RIF-sensitive, immediate weight-based 2HRZE/4HR per WHO guidelines achieves clinical cure, sputum conversion, and near-complete radiological resolution, as documented in this case. This integrated protocol should be adopted as standard practice at bronchoscopy-capable facilities across TB-endemic settings.