The ultrastructural features of plasmablastic lymphoma.

Plasmablastic lymphoma was originally described in 1997 by Delecluse et al. and is an aggressive variant of diffuse large B-cell non-Hodgkin lymphoma seen predominantly in a setting of acquired immunodeficiency syndrome and nearly always in extranodal sites. The authors have seen 10 cases in their department between 2001 and 2005. The patients' ages ranged from 24 to 39 years and there were 7 females and 3 males. In 7 cases where human immunodeficiency virus had been tested it was positive. Eight cases were extranodal and 2 cases involved lymph nodes. Five cases were followed up and 4 were confirmed dead within 5 months of diagnosis, verifying the aggressive nature of this condition. Histology showed large, polygonal tumor cells some of which had a slightly plasmacytic appearance. Six cases had a "starry sky" background. Immunohistochemical stains were negative in 1 case, while the other 9 cases were positive for CD138. Electron microscopy showed concentrically arranged rough endoplasmic reticulum in the cytoplasm in 9 cases. In 1 case the cells were too degenerate for evaluation. This study shows that the ultrastructural features are well developed and can help in distinguishing plasmablastic lymphoma from other light microscopically undifferentiated tumors.