Are renal microgranulomas related to inflammatory tubular destruction?

Two cases of renal microgranuloma formation are reported, one in a patient with known Crohn's disease and another in a case of acute renal allograft rejection. In both cases, the microgranulomas arose as a result of inflammatory tubular destruction, in a manner analogous to that seen in patients with ulcerative colitis arising adjacent to ruptured epithelial crypts in the large intestine. Microgranulomas may occur at multiple anatomical sites in Crohn's disease, although renal microgranulomas are very rare. Non-specific inflammatory tubular destruction should be considered as a cause of renal microgranuloma formation, in addition to systemic granulomatous diseases, such as tuberculosis, sarcoid, or Crohn's disease, when granulomas are seen in the presence of inflammatory tubular destruction in renal biopsies.