PARACORTICAL NODULAR T-CELL LYMPHOMA IDENTIFICATION OF AN UNUSUAL VARIANT OF PERIPHERAL T-CELL LYMPHOMA

Peripheral T-cen lymphomas (PTCLs) are regarded as diffuse proliferati ons. We describe an unusual paracortical nodular growth pattern in fou r nodal PTCLs that were initially interpreted as atypical lymphoid hyp erplasia in three patients and small B-cell lymphoma with plasmacytic differentiation in a fourth. The nodules were vague to easily discerni ble and produced minimal to partial architectural distortion. Sinuses were often open, and scattered cortical lymphoid follicles with atreti c to hyperplastic germinal centers were present. Clusters of tumor cel ls abutted some follicles in all cases, and in one case they exhibited focal T-zone expansion. Hypervascularity was not prominent, but a few nodules surrounded epithelioid venules, imparting an angiofollicular appearance. The nodules were composed primarily of small lymphocytes w ith irregular nuclei admired with scattered large transformed cells, b oth eel types having clear cytoplasm. Paraffin immunoperoxidase showed that the nodules were composed of T cells. Dendritic cell networks we re present only in follicular centers. Southern blot analysis found T- cell receptor gene rearrangements and a germline immunoglobulin gene c onfiguration in all four nodes. These paracortical clear cell nodules of clonal T cells may be a special type of PTCL. Alternatively, they m ay represent early foci of lymphoma or they may be a subgroup of T-zon e lymphoma. Paracortical nodular PTCL must be differentiated from atyp ical hyperplastic lesions and some B-cell lymphomas.