[Histopathological diagnosis by skin biopsy].

As post-transfusion graft-vs-host disease (GVHD) has poor prognosis, early diagnosis by skin biopsy is essential. The histopathology of the skin lesion includes a lymphocytic infiltration to the dermo-epidermal junction associated with vacuolization of the basal layer. Dyskeratotic or necrotic epidermal cells are scattered through the epidermis. Some of these necrotic cells are surrounded by a few lymphocytes (satellite cell necrosis). These histopathological findings are referred to as a lichenoid tissue reaction, but is not specific to GVHD, and can be seen in some types of drug eruption (toxic epidermal necrolysis type and erythema multiforme type). Final diagnosis will be confirmed by the clinical symptoms, such as liver dysfunction, diarrhea and pancytopenia.