Primary T-cell lymphoma of the thyroid.
A rare case of non-Hodgkin's malignant T-cell lymphoma of the thyroid in a 79-year-old woman is reported. Light microscopically, the tumor showed diffuse proliferation of lymphoid cells, revealing prominent nuclear irregularity and occasional multilobulated nuclei, and was diagnosed as a diffuse lymphoma of medium-sized cell type. Electron microscopically, the tumor cells were seen to possess irregularly indented nuclei. Immunologic surface marker studies showed that the lymphoma cells were positive for T-lymphocyte-lineage antigens, OKT4 and OKT11, and did not react with B-lymphocyte-associated antigens. These findings indicated that the lymphoma had a T-cell phenotype.