Granulomatous disease

Background

• Granulomatous inflammation is chronic inflammation that involves macrophages and T lymphocytes to wall off an infectious organism
• T cells are activated and in turn activate macrophages, which undergo morphological changes to become more epithelioid
• Creates two main types of granulomas: foreign body granulomas, and immune ganulomas
  • In immune granulomas, macrophages active T cells to produce IL-2

Differential Diagnosis

• Infections
• Mycobacteria
  • Tuberculosis: caseating granulomas, with acid-fast bacilli
  • Leprosy: non-caseating granulomas, with acid-fast bacilli in macrophages
  • Non-tuberculous mycobacteria
  • Buruli ulcer (Mycobacterium ulcerans)
  • BCG vaccination
• Fungi: histoplasmosis, coccidiomycosis, blastomycosis, sporotrichosis, aspergillosis
• , cryptococcosis
• Protozoa: toxoplasmosis, schistosomiasis
• Spirochetes
  • Syphilis: gummas, which contain a wall of histiocytes, plasma cell infiltrate, and necrotic central cells without loos of cellular outline
  • Treponema carateum
  • Treponema pertenue
• Bacteria
  • Cat scratch disease: rounded or stellate granulomas with central granular debris and neutrophils; giant cells are uncommon
  • Brucella, Yersinia, Whipple diseaes
• Vasculitis: GPA, eGPA, lymphomatoid vasculitis, polyarteritis nodosa, bronchocentric vasculitis, giant cell arteritis, systemic lupus erythematosus
• Other inflammatory disorders:
  • Sarcoidosis: non-caseating granulomas with abundant activated macrophages
  • Crohn disease: occasional non-caseating granulomas in intestinal wall
  • Primary biliary cirrhosis, hepatic granulomatous disease, Langerhan granulomatosis, Peyronie disease, Blau syndrome, hypogammaglobulinemia, Langerhan cell histiocytosis, immune complex disease
• Leukocyte oxidase defects: chronic granulomatous disease
• Hypersensitivity pneumonitis: farmer's lung, bird fancier's lung, mushroom worker's lung, suberosis (cork dust), bagassosis, maple bark stripper's lung, paprika splitter's lung, coffee bean lung, Spatlese lung
• Chemical exposures: beryllium, zirconium, silica, starch, talc
• Neoplasms: carcinoma, reticulosis, pinealoma, dysgerminoma, seinoma, reticulum cell sarcoma, malignant nasal granuloma
• Miscellaneous: lymphogranuloma, Kikuchi syndrome

Further Reading

• James DG. A clinicopathological classification of granulomatous disorders. Postgrad Medical J. 2000;76:457-465. doi: 10.1136/pmj.76.898.457