Morphology of Granuloma

Concentric layers of Granuloma

There are 4 concentric layers in a granuloma, however the clear distinction is difficult in reality due to overlapping. From inside to out:

1. Necrosis

• Caseating necrosis: Tuberculosis, Leprosy
• Coagulative necrosis: Buruli ulcer (M.ulcerans), Gumma containing central blood vessels (Syphilis)
• Fibrinoid necrosis: Aschoff bodies (Rheumatic granuloma), Rheumatoid granuloma, Sarcoid and Beryllium granulomas (rarely)
• Central abscess or microabscess with neutrophils and almost no giant cells (Pseudotuberculous granulomas): Infectious and usually stellate configuration
  • Yersinia pseudotuberculosis
  • Bartonella (Cat scratch disease)
  • Brucellosis
  • Tularemia
  • Lymphogranuloma venereum
  • Listerosis
  • Histoplasmosis
  • Cryptococcosis
  • Typhoid fever
• No necrosis i.e., non-caseating granuloma: Mnemonic – RBCS and LDH
  1. Reaction to foreign body
  2. Sarcoid granulomas – Berylliosis, Chron’s disease, Sarcodiosis
  3. Leprosy – Tuberculoid
  4. Drug reactions
  5. Hypersensitivty pneumonitis
  6. Toxoplasmosis

2. Giant cells, Epitheloid cells and Macrophages

• Epitheloid cells (Macrophages that are secretory and have lost phagocytic properties): Tuberculous granuloma, Sarcoid granuloma, Tumor associated granuloma
• Phagocytic histiocytes: Foreign body granuloma, Rheumatic and Rheumatoid granuloma
• Langhans giant cells (Horse shoe pattern of nuclear arrangement): Tuberculous granuloma (Tuberculosis, Leprosy, Syphilis)
• Foreign body giant cells (Haphazard and random nuclear arrangement): Foreign bodies like suture, talc, etc.
• Touton giant cells (Ring of nuclei surrounded by foamy pale cytoplasm): Xanthoma, Fat necrosis, Xanthogranulomatous inflammation, Dermatofibroma
• Palisading granuloma (Elongated nuceli of mononuclear phagocytes are palisaded): Rheumatoid nodules, Post-surgical necrobiotic granuloma in prostate/urinary bladder, etc.
• Asteroid bodies (stellate inclusions with numerous rays radiating from a central core) and Schaumann or conchoidal bodies (calcium deposited asteroid bodies): Sarcoid granuloma (Hard sore)
• No giant cells: Pseudotuberculous granuloma

3. Lymphocytes

• Especially prominent in immune granulomas.
• Lymphocytes secrete mediators that activate and alter macrophages and macrophage-derived cells located centrally.

4. Fibroblasts

• Walls off the lesion.

Pathophysiology and Morphology of Granuloma