Prognostic significance of immunophenotypes and a nodular pattern in primary mediastinal large B-cell lymphoma

To investigate the clinicopathological and prognostic significance of a nodular pattern and immunophenotypes in primary mediastinal large B-cell lymphoma (PMBL), histopathological features, including a nodular pattern and immunophenotypes, were analyzed in 58 Japanese PMBL patients. The patients were 23 men and 35 women with a median age of 31 years. The 4-year progression free survival (PFS) rate was 78%, and the 4-year overall survival (OS) rate was 89%. Among the histopathological and immunohistochemical features, Bcl6(+) (P = 0.013), MUM1(+) (P = 0.091), and pale cytoplasm (P = 0.064) were favorable prognostic indicators of PFS, and Bcl6(+) (P = 0.051) and MUM1(+) (P = 0.07) were favorable prognostic indicators of OS. Patients with Bcl2 negativity (n = 11) had 4-year PFS and OS rates of 100%. Histologically, a nodular pattern, resembling nodular sclerosis classical Hodgkin lymphoma (CHL), was observed in 22 patients (38%). However, this was not a significant prognostic indicator. In conclusion, Bcl6(+) , MUM1(+) , Bcl2(-) , and pale cytoplasm are candidate favorable prognostic indicators for PMBL and should be further examined in larger studies. We suggest that PMBL with a nodular pattern may belong to the same histological spectrum as nodular sclerosis CHL.