Fibrin Ring Granulomas

Fibrin ring  or “doughnut” granulomas are small, non-necrotizing granulomas with a very distinctive appearance that are usually found in the liver and bone marrow in patients with Q fever. These granulomas characteristically contain a ring-like structure consisting of fibrinoid material; they may or may not have a centrally located fat vacuole(s). This type of granuloma, although uncommon,  may be seen in many other conditions including a variety of infections (CMV, EBV, MAI, hepatitis A, infectious mononucleosis, visceral leishmaniasis, Lyme disease, Boutonneuse fever, toxoplasmosis) Hodgkin disease, non-Hodgkin lymphomas, and drug reactions.

Fibrin ring granuloma with central fatty vacuoles. Q fever. Liver

Fibrin ring granuloma. Q fever. Liver

Fibrin ring granuloma. Q fever. Liver