RESUMO
<p><b>OBJECTIVE</b>To study the clinicopathologic features of peripheral T-cell lymphoma, unspecified (PTL-U) with follicular pattern.</p><p><b>METHODS</b>The clinical data, hematoxylin and eosin-stained sections of lymph node biopsies and follow-up data of 18 cases of PTL-U associated with follicular growth pattern were reviewed and studied. Eight cases of reactive lymphoid hyperplasia were used as controls. Semi-quantitative observation by retiform micrometer rule was carried out. Immunohistochemical study was also performed in all cases. T-cell receptor and immunoglobulin heavy chain gene rearrangement studies were conducted by polymerase chain reaction-based method.</p><p><b>RESULTS</b>The median age of the patients was 53 years. The male-to-female ratio was 1.57:1 in lymphoma group. All of the lymphoma patients presented with superficial lymphadenopathy, with (8/18) or without B symptoms. Histologically, the lymphoma was characterized by follicles of various sizes and shapes. The T zones were expanded by medium-sized lymphoma cells which contained clear cytoplasm and irregular nuclei. Mitotic figures were commonly identified. Immunohistochemical study confirmed that the lymphoma cells were of T-lineage. The proliferative index, as highlighted by Ki-67, was higher [average = (38.24 +/- 13.42)%/mm2] than that in the control group. T-cell receptor gene rearrangement was demonstrated in 71.4% (10/14) of the lymphoma cases.</p><p><b>CONCLUSIONS</b>A definitive diagnosis of PTL-U with follicular pattern can be made on the basis of morphologic examination, immunohistochemical assessment and clinical features. Cases with atypical features can further be delineated by molecular analysis. Long-term follow up of these patients is prudent.</p>