Spontaneous regression of metastatic cancer cells in the lymph node: a case report

BACKGROUND: Spontaneous regression of a malignant tumor is the phenomenon of disappearance of cancer cells without any treatments and it can be induced by an enhanced tumor-targeting immune response. However, there has not been a comprehensive immunological overview to compare the tumor-regressed lymph nodes and metastatic lymph nodes in the same patient. CASE PRESENTATION: We conducted a histologic analysis of various immune cells in an Asian female patient with buccal cancer (squamous cell carcinomas), in which the spontaneous regression of metastatic lymphadenopathy was confirmed by surgical pathology. The immune cell profiles between the metastatic nodes and the tumor-regressed nodes were compared. Tumor regression was confirmed by hematoxylin & eosin and cytokeratin/Ki-67 staining. Distinct differences were observed in Foxp3(+) regulatory T (Treg) cells and CD56(+) natural killer (NK) cells; a higher density of Foxp3(+) Treg cells was found in metastatic lymph nodes and more infiltration of CD56(+) NK cells in tumor regressed lymph nodes. Other immune cell populations (CD4, CD8, CD20, CD68, CD86, CD123, CD11c, and mannose receptor) showed no discernible differences in marker expression in the nodes examined. CONCLUSION: Less recruitment of Treg and high infiltration of NK cells were key features in tumor-regressed lymph nodes. Modulation of Treg or NK cells may be a good therapeutic method to control lymph node metastasis.