Heterotopic salivary gland tissue in lymph nodes of head and neck: An immunohistochemical study.

Abstract

A total of 3174 lymph nodes obtained from 156 cases of neck dissection and 31 cases of parotidectomy were evaluated for presence of heterotopic salivary gland tissue. The intranodal salivary tissue was found in 19 cases of neck dissection and 21 cases of parotidectomy; and they were more frequent in the intraparotid (67.7% cases) than in the extraparotid cervical nodes (12.2% cases). Salivary gland heterotopia in the lymph nodes histologically showed mature acini, small ducts, striated ducts, immature ducts and acini similar in structure to those seen in fetal salivary glands with proliferating ductal structures (22.7%), oncocytic metaplasia (10.6%), hyperplasia of oncocytes with cyst formation (10.6%), cyst formation in ductal epithelia (16.7%) and sebaceous metaplasia (0.5%). Monoclonal antibody to cytokeratins PKK1 and KL1 staining was positive in luminal ductal cells. Cytokeratin K8.12 reactivity was positive in both the luminal and basal ductal cells in contrast to negative luminal ductal cells in extra nodal salivary ducts. Immunoreactivity of epithelial membrane antigen (EMA), lysozyme (LY), lactoferrin (LF), alpha1-an-tichymotrypsin and alpha1-antitrypsin was irregular. On the basis of histological and immunohistochemical findings, the authors conclude that salivary tissues in lymph nodes are immature gland type, have potential for cytodifferentiation and various lymphoepithelial lesions may arise from these heterotopic salivary gland tissues.