Last reviewed 01/2018

A granuloma - plural granulomas or granulomata - is a discrete region of granulomatous inflammation defined by its histology after biopsy:

  • epitheloid cells at its centre
  • fusion of epitheloid cells to form a foreign body giant cell - the key feature

There may also be:

  • lymphocyte mantle surrounding epitheloid cells
  • evidence of aetiological agent e.g. tuberculosis bacillus
  • fibroblast proliferation with or without fibrin deposition
  • plasma cells
  • less frequently, neutrophils

A tuberculous granuloma is termed a tubercle. Rheumatoid nodules of rheumatoid arthritis contain granulomas.

The causes of granulomas are detailed under granulomatous inflammation in the submenu.