Hematopoietic stem cell transplantation continues to be the mainstay of treatment for many hematologic dyscrasias and malignancies, including acute leukemias, lymphomas, and aplastic anemia. There can be significant complications, however, and often these complications are manifested in the skin as an eruption. Common among these are acute and chronic graft-versus-host disease, erythema multiforme, Stevens-Johnson syndrome/toxic epidermal necrolysis, eruption of lymphocyte recovery, staphylococcal scalded skin syndrome, morbiliform drug eruptions, infections, and toxic erythema of chemotherapy. These entities can show significant clinical and histopathologic overlap, yet accurate distinctions among them are critical to initiating appropriate clinical interventions. In this review, we will discuss the key clinical and histopathologic findings in each entity as well as appropriate differential diagnostic entities.