USEFULNESS OF FOLLICULAR DENDRITIC CELL PATTERN IN CLASSIFICATION OF PERIPHERAL T-CELL LYMPHOMAS

Classification of peripheral T-cell lymphomas based on morphological c riteria can present problems due to overlap in histological features a mongst the subtypes. An immunohistochemical study was designed to stud y the follicular dendritic cell patterns in 21 cases of peripheral T-c ell lymphoma which had been classified using the updated Kiel classifi cation. Three patterns of distribution were observed: 1 follicular den dritic cells not detected (3 cases); 2 follicular dendritic cells rest ricted to remnant follicle centres (7); 3 follicular dendritic cells p resent as an expanded network of cells exceeding the confines of germi nal centres (11). Ten out of 11 angioimmunoblastic lymphomas showed an expanded network of follicular dendritic cells. The only negative cas e showed features which, on review, were in keeping with a pleomorphic , medium and large cell lymphoma showing an unusual proliferation of s mall venules. Other than angioimmunoblastic lymphomas, only one other case showed follicular dendritic cell hyperplasia. This was an unclass ified peripheral T-cell lymphoma. We conclude that follicular dendriti c cell hyperplasia may be used an an aid to diagnosis of the angioimmu noblastic type of peripheral T-cell lymphoma, and we recommend the rou tine staining of these cells in typing of T-cell lymphomas to facilita te comparison between centres.