A histological study of salivary gland tissue in human lymph node

Abstract

There are few systemic examinations of salivary gland tissue in human lymph node (heterotopic salivary gland), so the significance of these tissue retrains obscure.In this study, we examined the appearance and histological pattern of these tissues in extraparotid lymph nodes obtained from 156 cases of radical neck dissection and intraparotid lymph node obtained from 31 cases of parotidectomy (parotid gland with salivary gland tumor) of various ages. We discussed the possible mode of development and significance of these tissues and the relation between these tissues and salivary gland tumors.The results are summarized as follows.1) In 19 of 156 cases of radical neck dissection, 27 extraparotid lymph nodes that included salivary gland tissue were found.2) In 21 of 31 cases of parotidectomy, 39 intraparotid lymph nodes that included salivary gland tissue were found.3) 3 types of invasive mode of salivary gland tissue into lymph node, a course through the hilus, a course through the capsule, a course through both the hilus and capsule, were found.4) These salivary gland tissues were composed of mature acini, small ducts resembling intralobular duct of adult parotid gland and striated ducts, immature acini and immature small ducts resembling fetal parotid gland tissue.5) Various appearances, cyst formation of duct system (16. 7%), oncocytic change of the duct epithelium (10.6%), adenomatous hyperplasia consisting of the oncocyte with minor cyst formation (10.6%), and proliferative appearance of duct epithelium (22.7%), were recognized in the salivary gland tissue in lymph nodes.6) In intraparotid gland lymph node, various changes, atrophy, inflammation, fat infiltration, of parotid gland did not influence the salivary gland tissue in lymph nodes.7) We believed that the salivary gland tissue in lymph nodes are of immature gland type and have active potentiality for cytodifferentiation. We thought that some salivary gland tumors, especially adenolymphoma, arose from salivary gland tissues in lymph nodes.8) We thought that further studies on salivary gland tissue in lymph nodes are significant for the elucidation of the development of salivary gland tumors.