Description
Atypical presentations of pulmonary tuberculosis (TB) often mimic other respiratory or systemic conditions, making diagnosis challenging. Instead of the classic symptoms like persistent cough, fever, and weight loss, patients may present with non-specific signs such as unexplained fatigue, hemoptysis, or even isolated radiological findings. In elderly, immunocompromised, or diabetic patients, TB may appear as a non-resolving pneumonia or lung mass. These atypical forms can delay diagnosis and treatment, increasing the risk of disease progression and transmission. Clinicians must maintain a high index of suspicion, especially in endemic regions or at-risk populations.
Summary Listen
- The presentation discusses Mycobacterium tuberculosis, the causative agent of tuberculosis (TB). It distinguishes between Mycobacterium tuberculosis complex, which includes species like tuberculosis, bovis, microti, and africanum, and non-tuberculous mycobacteria (NTM). The classification also follows Runaan's which includes photochromogens, scotochromogens, nonchromogens, and rapid growers.
- Pulmonary TB is categorized into primary, progressive primary, secondary, and miliary tuberculosis, while extra-pulmonary TB involves organs beyond the lungs like lymph nodes, pleura, bones, and CNS. Transmission occurs through aerosol droplets, leading to immediate clearance, latent TB infection (LTBI), reactivation TB, or primary TB disease, depending on host immunity.
- Granuloma formation, characterized by caseation necrosis surrounded by lymphocytes and epithelioid cells, is a key feature of TB infection. Primary TB involves the Ghon focus and Ghon complex, potentially progressing to progressive primary TB in immunocompromised individuals. Secondary TB, or reactivation TB, occurs due to waning immunity, while dissemination can lead to miliary TB.
- Typical TB symptoms include cough, low-grade fever, sputum, hemoptysis, anorexia, and weight loss. Radiological signs often involve the apices and posterior segments of the upper lobes, presenting as patchy consolidation with irregular margins. The tuberculin skin test (TST) is typically positive.
- Atypical TB presentations occur in immunocompromised patients (HIV/AIDS, malignancy, chemotherapy), elderly individuals, those with diabetes, chronic conditions, substance abuse issues and genetic factors. These patients may exhibit negative TST results and unusual symptoms like chest pain or fatigue, and may not have the usual upper-lobe predilection
- Atypical presentations include lower lung field TB, endobronchial TB, mediastinal/hilar lymph node involvement, tuberculomas, cryptogenic organizing pneumonia (COP) mimicking TB, ARDS, and non-resolving pneumonia. Diagnosis of these atypical presentations often requires bronchoscopy and biopsy.
- Endobronchial TB involves the tracheobronchial tree and can present with cough, chest pain, hemoptysis, and bronchorea. Bronchoscopic findings may reveal hyperemia, ulceration, or tumor-like lesions. Lower lung field TB involves the lower lobes and can be seen in patients with hepatic disease, diabetes, HIV, corticosteroid use, and silicosis.
- Tuberculomas are well-circumscribed nodules or masses resulting from encapsulated caseation necrosis. Mediastinal and hilar lymph node TB can present as isolated lymph node enlargement without lung infiltrates. COP can mimic TB radiologically with consolidation and crazy paving patterns, requiring biopsy for differentiation.
- HIV-related TB presentations depend on CD4 count, with lower counts leading to more atypical presentations. Immune reconstitution inflammatory syndrome (IRIS) can occur after ART initiation. Radiologically, HIV-TB may show non-cavitary lesions, consolidations, and lymph node enlargement.
- In conclusion, atypical TB presentations lack the typical upper lobe predilection and are frequently diagnosed through bronchoscopy, CT scans, and TBNAs/TBLBs. The presentation emphasized the importance of recognizing these variations for accurate diagnosis and treatment of tuberculosis.
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About the Speakers
Dr. Frank Mohan
Consultant Pulmonologist, Proprietor – Shine Chest and Critical Care Hospital, Assistant Professor – Santhiram Medical College, Andhra Pradesh
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