Lymph node involvement by direct extension in adenoid cystic carcinoma. Absence of classic embolic lymph node metastasis.

Thirty-four cases of adenoid cyctic carcinoma seen at the University of Virginia Hospital from 1946 to 1974 were reviewed, with special emphasis on lymph node involvement by tumor. Lymph node involvement was found in three cases of primary tumors of the submaxillary gland, and all of the affected lymph nodes were in the immediate vicinity of the primary tumor. Two lymph nodes were involved in two of the cases, and one node was involved in the third case. In all of these lymph nodes, adenoid cystic carcinoma was present in the soft tissue surrounding the node, and the tumor extended into the node. No metastatic tumors were observed in 46 lymph nodes removed incidentally at the time of local excision of the primary tumors in 10 additional cases or in 212 lymph nodes examined after unilateral radical neck dissections in six other cases. Five autopsies in this series showed no lymph node metastases. In this series of cases adenoid cystic carcinoma only invades lymph nodes in the immediate vicinity of the primary tumor. When lymph node involvement does occur, it does not result from embolic lymph node metastasis; rather, a direct invasion of the lymph node from tumor in the perinodal soft tissue occurs. Obviously, this small study does not completely exclude the possibility of embolic metastasis; however, if it does occur, it must be extremely rare.