Progressive Transformation of Germinal Centers (PTGC)
Follicular hyperplasia with progressively transformed germinal centers (PTGC) is a benign, non-clonal process of unknown etiology afflicting lymph nodes. It is most commonly seen in males in the 2nd decade of life. Patients develop asymptomatic, solitary enlarged lymph node, usually in the cervical region. PTGC follicles are larger than normal with an expanded mantle zone. They show increased number of small B lymphocytes, scattered centroblasts, prominent follicular dendritic cells, and numerous CD4+, CD57+ T-cells. Mantle zone B-cells migrate into the germinal center where they accumulate, expanding and disrupting the germinal center. There are many similarities to and association with nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL). This CD20 immunostain shows several large PTGC follicles in a background of follicular hyperplasia.