Three weeks after allogeneic bone marrow transplantation, a patient develops a maculopapular rash over the trunk, watery diarrhea, and rising bilirubin. Biopsy of affected skin shows apoptosis of basal keratinocytes with satellite lymphocytes. What is the underlying mechanism?

• A Recipient cytotoxic T cells attacking donor hematopoietic cells
• B Donor T cells recognizing recipient HLA antigens as foreign ✓
• C Preformed donor antibodies against recipient endothelium
• D Immune complex deposition in the intestinal vasculature

Explanation

Acute graft-versus-host disease occurs when immunocompetent donor T cells in the graft recognize recipient HLA antigens and attack host tissues, targeting skin, liver, and gastrointestinal tract. The histologic hallmark is apoptosis of epithelial cells accompanied by satellite necrosis, a single lymphocyte apposed to a dying keratinocyte. Preformed antibodies cause hyperacute solid organ rejection, not GVHD.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.