| We evaluated the clinicopathologic features of oxyphil parathyroid carcinomas and the expression of cytokeratin 14 ( CK 14 ) , the high affinity glucose transporter 4 ( Glut 4 ) , as well as the cell cycle proteins p 27 and Ki 67 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 CK 14 , Glut 4 , p 27 , and Ki 67 using the avidin biotin peroxidase system . ^^^ |