Histopathologic Features of Cutaneous Acute Graft-Versus-Host Disease in T-Cell-Depleted Peripheral Blood Stem Cell Transplant Recipients.

T-cell-depleted (TCD) allogeneic hematopoietic stem cell transplantation demonstrates similar efficacy and reduced incidence and severity of graft-versus-host disease (GVHD) in appropriately selected patients versus T-cell-replete transplantation. The histopathology of cutaneous acute GVHD (aGVHD) after TCD peripheral blood stem cell transplants (PBSCTs) is not described. We identified 13 cases of patients after TCD PBSCT, with definitive aGVHD, and 20 cases of non-aGVHD skin rash in patients after TCD PBSCT, during multidisciplinary review by a dermatopathologist, dermatologist, and transplant physician, incorporating clinical presentation, therapeutic response, and histopathology data. Histopathologic features of aGVHD and non-aGVHD skin rash in TCD PBSCT patients were compared to each other, and also to features recently reported for non-TCD transplant recipients. aGVHD and non-aGVHD skin rash in TCD PBSCT patients' biopsies had similar rates of epidermal acanthosis, dermal melanophages, neutrophils, plasma cells, eosinophils, and extravasated erythrocytes. While satellitosis, exocytosis and adnexal involvement slightly favored aGVHD, more notable differential findings favoring aGVHD were diffuse (vs. focal/absent) basal vacuolization (77% aGVHD vs. 25% non-aGVHD rash), involvement of the entire epidermis (vs. partial thickness) by necrotic keratinocytes (42% aGVHD vs. 0% non-aGVHD rash), and nondense (rather than exuberant) inflammatory infiltrates (77% vs. 20%). After filtering features seen in all TCD samples (epidermal acanthosis, dermal melanophages, neutrophils, plasma cells, eosinophils, and extravasated erythrocytes), the most distinct features belonging to aGVHD-positive TCD samples were diffuse basal vacuolization, slight rather than dense inflammatory infiltrates, and necrotic keratinocytes involving the entire epidermis. Awareness of these features may help when evaluating a skin rash occurring after a TCD transplant.