Calcitonin immunoreactivity in neoplastic and hyperplastic parathyroid glands: an immunohistochemical study

Previous studies have established that calcitonin (CT) and the calcitonin generelated peptide (CGRP) are synthesized and stored in subsets of hyperplastic parathyroid cells that also contain chromogranin B (Schmid, KW, et al. Lab Invest 73:90, 1995). The purpose of the current study was to determine whether other generic but variably expressed neuroendocrine markers, i.e., synaptophysin (SYN) and CD57 (Leu7), are also present in normal, hyperplastic, and neoplastic parathyroid tissue and to assess their relationships to the presence of CT.

Immunoperoxidase stains for chromogranin A (CgA), chromogranin B (CgB), SYN, CD57, and CT were performed on 54 hyperplastic, 17 neoplastic (adenoma), and 16 normal parathyroid glands. Sequential sections were stained with antibodies to CgA, CgB, SYN, CD57, and CT using standard avidin-biotin-peroxidase techniques.

CgA was diffusely expressed in all normal, hyperplastic, and neoplastic glands. In hyperplasia, CgB was variably expressed in 6 cases (11%), SYN in 6 (11%), CD57 in 15 (28%), and CT in 8 (15%). In adenomas, CgB was variably expressed in 3 (17%), SYN in 3 (17%), CD57 in 4 (23%), and CT in 4 (23%). All normal glands were negative for CgB, SYN, and CT, while CD57 was variably expressed in 17%. Of the 12 glands that were CT positive, 8 were also positive for CgB, 2 for SYN, and 9 for CD57. Four glands that were strongly and diffusely positive for CT were CgB and SYN negative.

CgB, SYN, and CD57 are markers for subsets of hyperplastic and neoplastic parathyroid glands. CT is also expressed in a significant proportion of hyperplastic and neoplastic parathyroid glands, and may be independent of the presence of CgB, SYN, or DD57. The significance of these findings in relationship to the abnormal calcium metabolism in patients with parathyroid hyperplasia remains to be determined.