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

granuloma morphology pathophysiology