Distribution of chromogranin and S100 protein in normal and abnormal adrenal medullary tissues.

The distribution of chromogranin and S100 protein was studied in 30 adrenal pheochromocytomas and 19 normal adrenal medullary tissues. Immunostaining in the tumors was compared with staining in sections of histologically normal medullae. Chromogranin showed diffuse cytoplasmic staining in all chromaffin cells. Chromogranin staining was consistently more intense in normal medullae, while less intense staining was present in most tumors from all four groups. S100 protein was present in the cytoplasm and nuclei of sustentacular cells surrounding chromaffin cells and in nerve branches. Many S100 protein-positive cells were present in normal medullae, in the two hyperplastic medullae, and in pheochromocytomas from patients with multiple endocrine neoplasia, type 2. Very few sustentacular cells were present in the other pheochromocytomas. These results indicate that S100 staining may be helpful in separating pheochromocytomas in patients with multiple endocrine neoplasia, type 2 disease from benign and malignant sporadic tumors.