ROSETTE-FORMING NON-HODGKINS-LYMPHOMAS

Homer Wright rosettes, typically found in neuroblastomas and consistin g of neoplastic cells surrounding an eosinophilic fibrillary centre wi thout a lumen, have been considered as an important finding in the dif ferential diagnosis of small round cell tumours. Rosettes in a neoplas m involving lymph nodes or bone marrow traditionally excluded a diagno sis of malignant lymphoma. In this report, we describe three cases of malignant lymphoma (two small lymphocytic and one diffuse large cell) with pronounced rosette formation. One of the two cases of small lymph ocytic lymphoma was observed in the bone marrow, the other small lymph otic lymphoma and the large cell lymphoma were in lymph nodes. The ros ettes consisted of neoplastic lymphoid cells, often with participation of reactive macrophages, and ultrastructurally they had a central mas s of interdigitating fibrillary cytoplasmic projections. Two cases wer e of B-cell lineage and one was of T-cell lineage. To the best of our knowledge, this is the first report of T-cell lymphoma with rosettes. Based on these findings, it is suggested that non-Hodgkin's lymphoma b e included in the differential diagnosis of rosette-forming round cell neoplasms.