NK/T-cell lymphoma, nasal type, γδ T-cell lymphoma, and CD8-positive epidermotropic T-cell lymphoma-clinical and histopathologic features, differential diagnosis, and treatment.

The cytotoxic lymphomas of the skin constitute a heterogeneous group of rare lymphoproliferative diseases that are derived from mature T cells and natural killer (NK) cells that express cytotoxic molecules (T-cell intracellular antigen- 1, granzyme A/B, and perforin). Although frequently characterized by an aggressive course and poor prognosis, these diseases can have variable clinical behavior. This review delivers up-to-date information about the clinical presentation, histopathologic features, differential diagnosis, and therapy of extranodal NK/T-cell lymphoma, nasal type, primary cutaneous gamma delta T-cell lymphoma, and primary cutaneous CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma.