The researchers conducted a retrospective study among patients developing MP eruptions after allogeneic hematopoietic stem cell transplantation. We compared the clinical and histopathological differences between an acute cutaneous GVHD (group 1) and other MP eruptions (group 2). We also determined the clinical prognostic indicators linked to critical GVHD severity, morbidity, and mortality. Prompt management of acute graft‐versus‐host disease or GVHD may prevent its morbidity and mortality. Maculopapular or MP eruption is a presenting sign of acute GVHD, but differentiation from other MP rash causes is challenging.

The study showed that among 95 patients identified, 75 met the classification criteria for acute graft‐versus‐host disease, and 25 had other MP eruptions. Palm and sole involvement were more frequently found in group 1 than in group 2. Comparing the histological features between the two groups, necrotic keratinocytes in basal and spinous layers, diffuse basal vacuolization, lymphocyte satellitosis, and subepidermal clefts were significantly more apparent in group 1. Among extracutaneous presentations, diarrhea alone and accompanied by hyperbilirubinemia and newly developed transaminitis suggested acute GVHD diagnosis. Mucosal involvement and blister formation correlated with severe acute GVHD. Skin and systemic GVHD severity associated with time to rash resolution, length of hospital stays, and mortality.