We investigated the role of OCT4 immunohistochemical staining in detecting
germ cell tumor lymph node metastases. Retroperitoneal
lymph node dissection is important for staging and treatment of testicular
germ cell tumors, and OCT4 is sensitive and specific for pluripotent testicular
germ cell tumors; however,
micrometastases, particularly from
seminoma, can be difficult to detect. We examined 262 lymph nodes in 45 retroperitoneal
lymph node dissection specimens from
germ cell tumor patients. Specimens were categorized as postchemotherapy and untreated retroperitoneal
lymph node dissection with or without clinical suspicion, based on
lymphadenopathy or elevated serum
germ cell tumor markers. Sections were stained with anti-OCT4 antibody. Twenty-one additional positive lymph nodes in 12 cases were detected to harbor scattered
seminoma cells, singly and in small clusters, from 256 previously considered benign in: untreated retroperitoneal
lymph node dissection with clinical suspicion (13% increase), postchemotherapy retroperitoneal
lymph node dissection (7%), and untreated retroperitoneal
lymph node dissection without suspicion (4%). However, no patient with an entirely negative dissection specimen was reclassified as positive. OCT4 immunohistochemistry detected scattered
seminoma cells and small clusters of
seminoma cells in lymph nodes previously considered to be benign for an overall increase of 8%, greatest in the setting of untreated retroperitoneal
lymph node dissection with clinical suspicion. However, immunohistochemistry did not convert any entirely negative specimen to positive. Future studies will be useful to determine whether the small volume of disease detected by immunohistochemistry has the same impact as routinely detected
lymph node metastases.