Peripheral T-cell lymphoma. A case report demonstrating morphologic heterogeneity and progression, and atypical immune reactions.

Peripheral T-cell lymphomas (PTCL) comprise a morphologically heterogeneous group of non-Hodgkin's lymphomas. The authors report on PTCL occurring in a 13-year-old girl, in whom they were able to evaluate histologic material from 11 biopsy specimens obtained during her 8-month clinical course. These biopsy specimens demonstrated morphologic progression from atypical immune reactions and diffuse mixed cell lymphoma observed at different anatomic sites during early stages of the disease to pleomorphic large cell lymphoma with erythrophagocytic tumor cells at the time of her death. Morphologic variability of PTCL that may occur during the course of a patient's illness was demonstrated, and discordant histologic findings in biopsy specimens obtained simultaneously from different anatomic sites was noted. The morphologic evolution of PTCL was expressed, in sequential biopsy specimens, by a progressive cellular pleomorphism with the appearance of large, often bizarre lymphoid cells. This was associated with the gradual diminution and disappearance of the B-cell areas and epithelioid histiocytic reactions which were present initially in the biopsy specimens. The findings suggest that some of the various morphologic descriptions of PTCL given in the literature may represent transient histologic expressions of the lymphoma at various stages in its natural history.