A focal area of granulomatous inflammation – consisting of multinucleate macrophages

Histology:

• Epithelioid appearance of macrophages, surrounded by mononuclear leukocytes (mainly lymphocytes and plasma cells)
• As lesion matures – develops a rim of fibrous CT

Infectious granulomas – also called immune granulomas because:

• Macrophages ingest resistant bacteria (eg. Mycobacteria) → activate T cells → produce IFN gamma → causes transformation of macrophages into giant cells
• Giant cells – also observed in foreign body reactions eg. sutures and amalgam