Distinctive Features in the Circumferential Structure of the Capsule of Parotid Gland Adenolymphoma.

From May 1984 to September 1991, 17 patients (male: 16, female: 1, average age:64) with parotid gland adenolymphoma were treated surgically in my department of otolaryngology. I have already described the distinctive features in the circumferential structure of the capsule of benign parotid gland pleomorphic adenoma. This time I studied parotid gland adenolymphomas, which are considered to have an entirely different origin from pleomorphic adenomas. In 13 patients the entire capsule around the tumor was very thin and there was no capsuler invasion by the tumors as is often found with pleomorphic adenomas. In two patients the capsules were partly thick but contained few duct tissues. Nine patients had partial defects of their capsules, the histological features of which were similar to the defective parts of the capsules of normal lymphnodes in the parotid gland. The atrophy of the lobules surrounding the tumor was less than that seen in pleomorphic adenomas. The histological findings in the capsule and the parotid gland tissue surrounding adenolymphomas were very different from those of pleomorphic adenomas. Furthermore, in six lymphonodes contained in the parotid gland, there were small adenolymphomas. These findings suggest that the greater part of adenolymphoma capsules originates in the capsules of the lymphnodes contained in the parotid gland.