Definition/General
Introduction:
Tuberculosis in sputum cytology represents chronic granulomatous inflammation caused by Mycobacterium tuberculosis
It is a major public health problem globally, especially in developing countries
Cytological diagnosis can be challenging and often requires correlation with microbiological findings.
Origin:
Caused by Mycobacterium tuberculosis complex organisms
Airborne transmission through droplet nuclei
Primary infection may be asymptomatic
Reactivation occurs with immunocompromise
Chronic granulomatous inflammation is characteristic response.
Classification:
Classified by clinical presentation
Primary tuberculosis (first infection)
Secondary/reactivation tuberculosis
Pulmonary tuberculosis
Extrapulmonary tuberculosis
Miliary tuberculosis
Drug-resistant tuberculosis (MDR-TB, XDR-TB).
Epidemiology:
Major global health problem
High prevalence in developing countries
HIV coinfection increases risk significantly
Drug resistance emerging concern
More common in immunocompromised patients
India highest burden globally.
Clinical Features
Presentation:
Chronic cough (>2 weeks duration)
Hemoptysis
Weight loss and night sweats
Fever (often low-grade)
Fatigue and malaise
Chest pain
Breathlessness with advanced disease.
Symptoms:
Persistent cough (90% of patients)
Sputum production (purulent or blood-tinged)
Hemoptysis (25-50%)
Constitutional symptoms (fever, weight loss, night sweats)
Chest pain (pleuritic)
Dyspnea (advanced cases).
Risk Factors:
HIV infection (major risk factor)
Malnutrition
Diabetes mellitus
Immunosuppressive therapy
Crowded living conditions
Substance abuse
Chronic kidney disease
Advanced age.
Screening:
Sputum smear microscopy (AFB stain)
Chest X-ray
Tuberculin skin test (TST)
Interferon-gamma release assays (IGRA)
GeneXpert MTB/RIF
Sputum culture
High-risk population screening.
Master Tuberculous Pulmonary Changes Pathology with RxDx
Access 100+ pathology videos and expert guidance with the RxDx app
Gross Description
Appearance:
Purulent sputum with thick consistency
Blood-streaked or frankly bloody
Yellow-green or rust-colored
Mucopurulent appearance
Caseous material may be present
Foul odor (secondary bacterial infection).
Characteristics:
High cellularity
Inflammatory debris
Caseous necrosis material
Thick, viscous consistency
Variable volume
Morning specimens often most cellular.
Microscopic Description
Immunohistochemistry
Positive Markers:
CD68 (macrophages/epithelioid cells)
CD163 (M2 macrophages)
Lysozyme (macrophages)
Alpha-1-antitrypsin
Vimentin (mesenchymal origin)
S-100 (weak in some macrophages).
Negative Markers:
Cytokeratin (AE1/AE3, CK5/6, CK7)
CD45 (leukocyte common antigen) in epithelioid cells
TTF-1 (negative)
p63 (negative)
Napsin A (negative).
Diagnostic Utility:
Limited role in TB diagnosis
CD68 positivity confirms macrophage origin
Helps exclude malignancy
Distinguishes from epithelial cells
AFB stain more important
PCR and culture definitive.
Molecular/Genetic
Differential Diagnosis
Similar Entities:
Other granulomatous infections
Sarcoidosis
Malignancy (carcinoma, lymphoma)
Fungal infections
Foreign body reaction
Pneumoconiosis.
Distinguishing Features:
TB: AFB positive, caseous necrosis, clinical correlation
Sarcoidosis: Non-caseating granulomas, AFB negative
Malignancy: Atypical cells, cytokeratin positive
Fungal: Special stains positive (PAS, GMS)
Foreign body: Polarizable material
Pneumoconiosis: Occupational history.
Diagnostic Challenges:
AFB-negative TB
Paucibacillary disease
Mixed infections
Drug-resistant TB
TB-malignancy coexistence
Atypical mycobacteria.
Sample Pathology Report
Template Format
Sample Pathology Report
Complete Report: This is an example of how the final pathology report should be structured for this condition.
Specimen Information
Sputum specimen, [collection method], [volume] ml
Specimen Adequacy
Adequate with [cellularity level] and inflammatory cells
Inflammatory Pattern
Chronic granulomatous inflammation with [specific features]
Cellular Findings
Epithelioid cells and [giant cell types] present
Necrosis
Caseous necrosis: [present/absent]
AFB Stain
Acid-fast bacilli: [seen/not seen]
Diagnosis
Chronic granulomatous inflammation, [consistent with/suspicious for] tuberculosis
Clinical Correlation
Correlate with clinical findings and chest imaging
Recommendations
Mycobacterial culture. GeneXpert MTB/RIF. Drug sensitivity testing if culture positive.