Histologic and immunohistologic features of the cases classified as NLRCHD.

(A) By conventional histology a nodular growth pattern reminiscent of NLPHD was visible at low power (H&E-stained). (B) In most of the cases, an intact or atrophic germinal center (highlighted by long arrow) could be found at the periphery of such a nodule (H&E-stained). The neoplastic cells were found to be distributed within the expanded mantle zone (short arrows). By morphology, they usually corresponded to RS cells. Also, cells without prominent eosinophilic nucleoli could be found (inset). (C) The neoplastic cells showed strong expression of CD30. (D) An expression of CD15 by the neoplastic cells was also noted (immunostain with the anti-CD15 monoclonal antibody C3D1, APAAP method). (E) The NLRCHD nodules consisted of small B cells as disclosed by the immunostains for CD20. (F) In 30% of the cases, the neoplastic cells (arrows) did show a CD20 expression.