Hyperplasia of vagal and carotid body paraganglia in patients with chronic hypoxemia.

Vagal and carotid body paraganglia were obtained from 43 randomly selected autopsies performed at the National Naval Medical Center. In each case, tissue from both sides was step sectioned and comparatively studied. The mean combined weight of carotid bodies in 37 control patients was 25.9 mg. There was good correlation between size and number of separate paraganglia comprising the vagal body (seven left, six right). Lobules were closely related to the ganglion nodosum and were actually within it in three instances. Tissue resembling parathyroid was encountered within 4 of the 86 resected vagus nerves. Lymphocytic infiltration occurred in carotid and vagal body paraganglia of 28% and 16% of patients, respectively. There was Schwann cell proliferatation in carotid body lobules of 2 patients; in another patient, talc emboli were present. The mean combined weight of carotid bodies in 6 patients with chronic hypoxemia was 47.6 mg, significantly greater than in the control group; in each case, lobules were enlarged. Chief cell hyperplasia occurred in vagal body paraganglia of 2 patients; in two other patients, lobules were large with equal proliferation of constituent cells. These morphologic findings indicate that in patients with chronic hypoxemia some vagal body paraganglia can be ascribed a chemoreceptor role similar to but probably less important than that of the carotid body.