Oxyphil
parathyroid carcinomas are uncommon
neoplasms, and the clinicopathologic features of these
tumors are largely unknown. We evaluated the clinicopathologic features of oxyphil
parathyroid carcinomas and the expression of
cytokeratin 14 (CK14), the high-affinity
glucose transporter-4 (Glut-4), as well as the
cell cycle proteins p27 and Ki67 and compared these with oxyphil
parathyroid adenomas and chief cell
parathyroid adenomas and
carcinomas.
Formalin-fixed,
paraffin-embedded archival tissues from primary (n = 6) and recurrent (n = 4) oxyphil
carcinomas were analyzed and compared with chief cell
parathyroid carcinomas (n = 12), oxyphil
parathyroid adenomas (n = 38), and chief cell
parathyroid adenomas (n = 17) by immunohistochemistry for CK14, Glut-4, p27, and Ki67 using the
avidin-
biotin peroxidase system. Patients with primary oxyphil and chief cell
carcinoma presented with high levels of serum
calcium (n = 15.5 and 13.7 mg/dL, respectively). Approximately half the patients in each group died of disease. The Ki67 labeling index was higher (4.9 vs 1.9) and the p27 index lower (23 vs 66) in primary oxyphil
carcinoma compared with primary oxyphil
adenomas. CK14 was expressed in most oxyphil
adenomas (35 of 38 cases) but not in oxyphil
carcinomas (0 of 10 cases). Glut-4 was more commonly expressed in both groups of
adenomas compared with
carcinomas. These results show that oxyphil
parathyroid carcinomas are functional
malignancies similar to chief cell
carcinomas and are associated with
hypercalcemia, recurrence, and death. Expression of CK14 is very different in oxyphil
adenomas compared with
carcinomas. Although distinction between
parathyroid adenomas and
carcinomas can only be made by histopathologic and clinical findings, these results suggest that immunostaining for CK14, p27, and Ki67 may provide additional information to help distinguish between difficult cases of
parathyroid adenomas and
carcinomas. These findings also indicate that the same histopathologic features should be used to diagnose oxyphil and chief cell
parathyroid carcinomas.