The impact of histopathologic examination of graft-versus-host disease in the era of reduced-intensity conditioning regimen: a study from the Gruppo Italiano Trapianto di Midollo Osseo.

Reduced-intensity conditioning regimens have reshaped the clinical presentation of graft-versus-host disease after hematopoietic stem cell transplants. However, histopathologic features of graft-versus-host disease following reduced-intensity conditioning regimens have not been fully characterized. In a series of 112 biopsies (skin, n = 60; gastrointestinal [GI] tract, n = 44; liver, n = 8), we described the morphologic profile of graft-versus-host disease following reduced-intensity conditioning and investigated whether histopathologic changes of graft-versus-host disease following reduced-intensity conditioning have a diagnostic and/or prognostic value. Forty-four patients (49.5%) experienced acute graft-versus-host disease, 2 (2.2%) late-onset acute graft-versus-host disease (grade I, n = 13; grade II-IV, n = 33), 24 (27.0%) chronic graft-versus-host disease (de novo n = 12, progressive n = 12) and 19 (21.3%) overlap syndrome. In the skin, we observed: (i) phase-nonspecific changes, such as acute graft-versus-host disease features in chronic graft-versus-host disease patients (n = 4/24; 16.6%), (ii) subtle alterations such as superficial fibrosis in widened dermal papillae (n = 8), in acute graft-versus-host disease/late-onset graft-versus-host disease (n = 6/46; 13.0%) or chronic graft-versus-host disease (n = 2/24, 8.3%) patients, and (iii) features of chronic and acute graft-versus-host disease coexisting in the same specimen in overlap syndrome (n = 3/19; 15.7%). In the GI tract, we did not demonstrate peculiar features differing from those commonly observed in the myeloablative setting. By univariate analysis, a reduced overall survival was associated with graft-versus-host disease type (chronic graft-versus-host disease P = .006, acute graft-versus-host disease P = .03), older age (P = .04), and histopathologic diagnosis of "consistent with" + definite graft-versus-host disease (P = .02). Histopathologic diagnosis retained an independent prognostic value by multivariate analysis (P = .01). The present study indicates that pathologists should be aware of the peculiar morphologic changes of cutaneous graft-versus-host disease following reduced-intensity conditioning and further recommends histopathology in the diagnostic workup of graft-versus-host disease in patients undergoing reduced-intensity conditioning regimen.