Definition/General
Introduction:
Tuberculous ascites is caused by Mycobacterium tuberculosis infection of peritoneum
Represents 1-3% of all ascites cases globally
Higher prevalence in endemic areas like India (10-15%)
Wet type (ascitic) vs dry type (adhesive)
Often part of disseminated tuberculosis.
Origin:
Results from hematogenous spread from pulmonary TB
Lymphatic spread from mesenteric lymph nodes
Direct extension from intestinal TB
Reactivation of latent peritoneal foci
Primary peritoneal TB (rare).
Classification:
Classified as exudative ascites
SAAG <1.1 g/dL
Protein >2.5 g/dL
ADA levels >33 U/L (highly suggestive)
Wet type (90% cases) vs dry type (10% cases).
Epidemiology:
Peak incidence in 20-40 years age group
Female predominance (3:1 ratio)
High prevalence in developing countries
Associated with HIV co-infection (15-20% cases)
Malnutrition predisposes to infection.
Clinical Features
Presentation:
Insidious onset abdominal distention
Low-grade fever with night sweats
Abdominal pain (dull, aching)
Weight loss and anorexia
Chronic cough may be present
Menstrual irregularities in women.
Symptoms:
Abdominal distention (85% cases)
Low-grade fever (70% cases)
Weight loss (80% cases)
Abdominal pain (60% cases)
Night sweats (65% cases)
Anorexia (75% cases)
Diarrhea (30% cases).
Risk Factors:
HIV infection
Immunocompromised state
Malnutrition
Diabetes mellitus
Chronic kidney disease
Silicosis
Endemic area residence
Previous tuberculosis history.
Screening:
Tuberculin skin test (TST)
Interferon-gamma release assays
CT abdomen showing peritoneal thickening
Laparoscopy (gold standard for diagnosis)
ADA levels in ascitic fluid.
Master Tuberculous Ascites Pathology with RxDx
Access 100+ pathology videos and expert guidance with the RxDx app
Gross Description
Appearance:
Ascitic fluid is straw-colored to turbid
May be hemorrhagic in some cases
Moderate to large volume
Viscous consistency
Clear to slightly cloudy
Odorless typically.
Characteristics:
Exudative characteristics
Protein >2.5 g/dL
SAAG <1.1 g/dL
ADA >33 U/L (highly suggestive)
Low glucose may be present
Elevated LDH.
Size Location:
Generalized ascites
Loculated in complicated cases
Peritoneal thickening on imaging
Omental involvement
Adhesions may be present.
Multifocality:
Diffuse peritoneal involvement
Mesenteric lymphadenopathy
Omental thickening
Bowel wall involvement
Hepatic surface nodules may be seen.
Microscopic Description
Histological Features:
Ascitic fluid shows lymphocytic predominance (60-90%)
Total cell count 150-4000 cells/μL
Activated lymphocytes and plasma cells
Epithelioid cells (when present)
Reactive mesothelial cells.
Cellular Characteristics:
Small mature lymphocytes predominant
Large activated lymphocytes
Plasma cells with eccentric nuclei
Epithelioid cells (pathognomonic when present)
Multinucleated giant cells (rare).
Architectural Patterns:
Dispersed lymphocytes
Epithelioid cell clusters (diagnostic)
Loose granulomatous aggregates
Reactive mesothelial proliferation
Inflammatory background.
Grading Criteria:
No specific grading system
ADA levels >33 U/L supportive
Epithelioid cells highly suggestive
AFB positivity rare (5-10% cases)
PCR positivity increases diagnostic yield.
Immunohistochemistry
Positive Markers:
CD3 for T-lymphocytes
CD68 in epithelioid cells and macrophages
CD138 in plasma cells
Lysozyme in epithelioid cells
Calretinin, WT1 in mesothelial cells.
Negative Markers:
Cytokeratins (except mesothelial cells)
CEA to exclude adenocarcinoma
CD20 (B-cells fewer than T-cells)
CD15, CD30 to exclude lymphoma.
Diagnostic Utility:
IHC has limited diagnostic role
T-cell predominance supports TB diagnosis
Epithelioid cell markers confirm granulomatous inflammation
Excludes malignancy when differential unclear.
Molecular Subtypes:
Th1 immune response predominant
CD4+ T-helper cells increased
Interferon-gamma production
TNF-alpha, IL-2 elevated.
Molecular/Genetic
Genetic Mutations:
No mutations in host cells
Mycobacterial DNA detection by PCR
IS6110 sequence specific for M
tuberculosis
16S rRNA gene amplification
GeneXpert MTB/RIF for rapid diagnosis.
Molecular Markers:
Adenosine deaminase (ADA) >33 U/L
ADA2 isoenzyme predominant
Interferon-gamma elevated
TNF-alpha, IL-2 increased
Lysozyme levels elevated.
Prognostic Significance:
Good prognosis with appropriate treatment
Treatment duration 6-9 months
Drug resistance affects outcomes
HIV co-infection complicates treatment
Early diagnosis improves prognosis.
Therapeutic Targets:
Anti-tubercular therapy (ATT)
HRZE regimen initially
Treatment duration 6-9 months
Drug sensitivity testing
Corticosteroids in selected cases.
Differential Diagnosis
Similar Entities:
Malignant ascites (carcinomatosis)
Cirrhotic ascites (portal hypertension)
Nephrotic syndrome
Pancreatic ascites
Chylous ascites
Fungal peritonitis.
Distinguishing Features:
TB: ADA >33 U/L
TB: Lymphocytic predominance
TB: SAAG <1.1
Malignant: Cytological atypia
Cirrhotic: SAAG >1.1
Chylous: High triglycerides.
Diagnostic Challenges:
Low AFB positivity (5-10%)
Culture yield variable (20-83%)
Overlap with other lymphocytic effusions
Laparoscopy often needed for definitive diagnosis
PCR improves diagnostic accuracy.
Rare Variants:
Dry tuberculous peritonitis (plastic type)
Wet-dry combination
Hemorrhagic tuberculous ascites
Multi-drug resistant TB
Tuberculous peritoneal-pleural communication.
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
Peritoneal fluid, volume [X] mL, straw-colored to turbid
Adequacy
Adequate for cytological evaluation
Cellularity
Moderate cellularity with [X] cells/μL
Cell Differential
Lymphocytes: [X]% (predominantly small mature), Mesothelial cells: [X]%, Macrophages: [X]%, Neutrophils: [X]%
Morphological Features
Predominance of lymphocytes with occasional epithelioid cells [if present]. Reactive mesothelial cells noted.
Epithelioid Cells
Epithelioid cells: [Present/Absent] - [Description if present]
AFB Staining
AFB staining: [Positive/Negative for acid-fast bacilli]
Additional Studies
ADA level: [X] U/L (>33 U/L suggestive of tuberculosis)
Malignant Cells
No malignant cells identified
Final Diagnosis
Peritoneal fluid cytology suggestive of tuberculous peritonitis
Comment
Findings suggest tuberculous etiology. Recommend correlation with ADA levels, imaging findings, and clinical presentation. Consider laparoscopy for definitive diagnosis.