This is intestinal transplant–associated microangi- opathy (ITAM), a life-threatening complication of allogeneic bone marrow transplantation. Trans- plant-associated microangiopathy can be systemic (characterized by hemolysis with schistocytes, thrombocytopenia, renal and neurologic dysfunction, and elevated lactate dehydrogenase) or isolated to
the intestine.1 The incidence is unknown, but the condition is likely underrecognized. Risk factors for ITAM
are intestinal GVHD, CMV colitis, and treatment with
calcineurin inhibitors. Figures A and B show the discrete
ulcers scattered along the entire colon and small whitish
plaques (thin arrows in Figure A). The latter was a manifestation of pseudolipomatosis (innocuous small air bubbles in the mucosa).
Pathology is shown in Figures C and D. Pathology is the
gold standard for diagnosis: Microangiopathy (thick ar-
rows), crypt loss, and platelet thrombi (thin arrows) are
present. Apoptotic bodies in the crypts can be seen (verti-
cal arrows in D).
This condition has to be distinguished from GVHD: The
therapy offers few good options — intensified immuno-
suppression/calcineurin inhibitors are discontinued, an
approach opposite of the treatment for GVHD. 2
Recombinant thrombomodulin can be tried. Prognosis
is poor as underlined by mortality reported between 30%
and 57% of cases.
Tapering of immunosuppression in the patient proved
efficacious. He was discharged 6 days later with consider-
able reduction of volume of stools. n
1. Pettit, A.R., Clark, R.E. Thrombotic microangiopathy following bone marrow transplantation. Bone Marrow Transplant. 1994;14:495-504.
2. Nishida, T., Hamaguchi, M., Hirabayashi, N. et al. Intestinal thrombotic microangiopathy after allogeneic bone marrow transplantation: a clinical imitator of acute enteric graft-versus-host disease. Bone Marrow Transplant.
From What’s Your Diagnosis? on page 5