Evolution and progression in malignant lymphoma of Waldeyer's ring: histopathological and immunohistochemical studies of three cases of total tonsillectomy.

Histopathological and immunohistochemical studies were performed in three patients with malignant lymphoma of Waldeyer's ring (ML-WR) who underwent total tonsillectomies. Residual reactive follicles mixed with neoplastic follicles were present beneath the surface epithelium of the crypts at the base of the tonsils. The neoplastic follicles were growing expansively and fusing with each other until finally, the process resulted in a diffuse proliferation pattern. Both of the tumor and follicular center cells (FCCs) in the reactive follicles were positive for LN-1; accordingly, the ML-WR tumor cells were considered to originate from FCCs. Anti-S-100 positive follicular dendritic cells (FDCs) were much scarcer in the neoplastic follicles of the tonsils than in the neoplastic follicles of the lymph nodes. FDCs may have a role to play in regulating the proliferation pattern of tumor cells in ML-WR.