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 J apanese 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 .