Lymphocytic infiltration in undifferentiated nasopharyngeal cancer

Background: Undifferentiated nasopharyngeal carcinoma (NPC) is characterize d by prominent lymphocytic infiltration. Although the lymphoid infiltrate i n NPC has been examined extensively in morphologic and immunocytochemical s tudies, the significance of this lymphoid infiltrate and its correlation wi th prognosis has been a subject of controversy for years. Objective: To elucidate the significance of lymphoid infiltration in undiff erentiated NPC. Design: Evaluation of the relationship between lymphocytic infiltration in NPC and cervical lymph node status, ultrastructural examination of the lymp hoid infiltrate, and assessment of lymphocytic infiltration as an independe nt prognosticator of regional node metastasis. Materials and Methods: Lymphocytic infiltration was evaluated quantitativel y in 20 cases of undifferentiated NPC using light microscopy. Four cases of undifferentiated NPC were processed for conventional electron microscopy. The effects of degree of lymphocytic infiltration, age, and tumor stage on cervical nodal metastasis were analysed using the logistic regression model . Results: The degree of lymphoid infiltration correlated with cervical nodal metastasis (P<.001). Ultrastructural evidence of lymphocytes destroying ca ncer cells was seen. Lymphocytic infiltration was found to be an independen t factor affecting cervical nodal metastasis (P=.02, univariate analysis; P =.03, multivariate analysis). Conclusions: The lymphoid infiltrate is beneficial in undifferentiated NPC, and its presence may deter regional metastasis of cancer cells to the cerv ical nodes.