Cutaneous toxoplasmosis histologically mimicking graft-versus-host disease

The dermatology service is frequently consulted to assess cutaneous eruptions after hematopoietic stem cell transplantation. We describe a case of cutaneous toxoplasmosis in a stem cell transplant patient where toxoplasmosis trophozoites elicited a reaction pattern mimicking an interface dermatitis. At first blush, these findings may be misinterpreted as either a reaction to a drug or graft-versus-host disease. We hope that this case will prove helpful for dermatopathologists in asserting the correct diagnosis of cutaneous toxoplasmosis-if left untreated or treated incorrectly, this disease has a dismal prognosis.