Granulomas

Related Subjects: | Chronic Granulomatous Disease | Granulomatous Diseases

🧩 Granulomatous diseases are conditions in which the immune system forms granulomas - organised clusters of macrophages, lymphocytes, and giant cells - as a defence mechanism when unable to eliminate a pathogen or trigger. ⚠️ Granulomas are a non-specific pathological pattern and must be interpreted in clinical context.

🔬 Characteristics of Granulomas

• Structure 🧱 :
  • Aggregates of macrophages (epithelioid cells), lymphocytes, and multinucleated giant cells.
  • Caseating granulomas (central necrosis, cheese-like appearance) → classic of TB & fungal infections.
  • Non-caseating granulomas (no necrosis) → sarcoidosis, Crohn’s disease.
  • Occasional calcification in chronic granulomas.
• Formation 🔄 :
  • Triggered by persistent antigenic stimulus.
  • Macrophages → epithelioid cells → multinucleated giant cells (Langhans type or foreign-body type).
  • T-helper (CD4+) cells, TNF-α, and interferon-γ play central roles.

🧾 Common Granulomatous Diseases

• Tuberculosis 🫁 :
  • Mycobacterium tuberculosis → caseating granulomas.
  • Symptoms: chronic cough, fever, night sweats, weight loss.
  • May cavitate and spread (miliary TB).
• Sarcoidosis 🌿 :
  • Autoimmune → non-caseating granulomas.
  • Affects lungs, lymph nodes, eyes, skin.
  • Symptoms: cough, dyspnoea, erythema nodosum, uveitis.
• Granulomatosis with Polyangiitis (GPA) 🩸 :
  • Necrotising vasculitis with granulomas.
  • Affects ENT, lungs, kidneys.
  • Symptoms: sinusitis, haematuria, cough, pulmonary nodules.
  • Lab: c-ANCA (PR3 antibodies).
• Leprosy 🧕 :
  • Mycobacterium leprae → granulomas in skin, nerves, airway.
  • Symptoms: anaesthetic patches, neuropathy, deformities.
• Histoplasmosis 🍂 :
  • Fungal → caseating granulomas in lung & lymph nodes.
  • Can mimic TB; disseminates in immunocompromised hosts.
• Cryptococcosis 🍄 :
  • Cryptococcus neoformans → lung + brain granulomas.
  • Symptoms: cough, chest pain, meningitis in HIV.
• Cat-Scratch Disease 🐱 :
  • Bartonella henselae → granulomatous lymphadenitis.
  • Symptoms: fever, fatigue, tender lymph nodes after cat scratch/bite.

🔍 Diagnosis

• Clinical 🩺 : Symptoms vary by organ system.
• Imaging 🖼️ : CXR/CT (lung granulomas), MRI/CT (CNS involvement).
• Lab 🧪 :
  • Blood tests (inflammatory markers, serology).
  • Tuberculin skin test / interferon-gamma release assay (TB).
  • ANCA (vasculitis), ACE level (sarcoidosis).
• Histology 🔬 : Biopsy shows granuloma type (caseating vs non-caseating).

💊 Treatment

• Infectious 🌡️ :
  • TB → multi-drug therapy (RIPE regimen).
  • Leprosy → rifampicin + dapsone ± clofazimine.
  • Fungal infections → antifungals (Itraconazole, Amphotericin B).
• Autoimmune 🛡️ :
  • Sarcoidosis/GPA → corticosteroids, methotrexate, azathioprine, biologics (rituximab for GPA).
• Supportive 🩹 :
  • Pain control, oxygen therapy for lung disease, immunosuppression monitoring.

⚠️ Clinical Pearls

• Always distinguish infectious vs autoimmune → treatment differs radically (antibiotics vs immunosuppression).
• Caseating granulomas → usually TB/fungal. Non-caseating → sarcoid, Crohn’s, GPA.
• Some granulomas calcify → appear as incidental CXR/CT findings.
• Chronic granulomas can lead to fibrosis and organ dysfunction.

📚 Summary

Granulomatous diseases represent a spectrum of infectious 🦠, autoimmune 🌿, and inflammatory 🔥 conditions. Histology (caseating vs non-caseating), microbiology, and systemic context guide diagnosis. Treatment may involve antimicrobials, antifungals, corticosteroids, or immunosuppressants, tailored to the underlying cause.