Fat staining in parathyroid disease--diagnostic value and impact on surgical strategy: clinicopathologic analysis of 191 cases

The study comprised 191 cases of surgically treated hyperparathyroidism, with all principal types of parathyroid disease represented. At least two complete glands stained with a modified isopropanol oil red O method for fat, in addition to sections stained with hematoxylin-eosin, were available in each case. On the basis of the morphologic evaluation and the clinical follow-up data, it is concluded that access to two complete glands and the use of fat staining allow highly reliable intraoperative distinction between adenoma and hyperplasia. Of 105 patients followed up for at least one year (mean, 20 months) in whom adenomas were diagnosed, a single possible error was identified. In each of 68 cases classified as hyperplasia on the basis of two abnormal glands, every additional complete gland available (total, 182 glands) was at least partially abnormal, with distinct signs of hyperactivity, irrespective of size. The rate of equivocal findings for cases in which two glands were available (probably adenoma but hyperplasia not excluded) was 8 per cent in 165 cases of primary hyperparathyroidism. These results justify limitation of surgery to one side of the neck in patients in whom adenoma is diagnosed on the basis of a complete, functionally normal (inactive) gland in addition to the presumed adenoma. Thus, the methods described provide a basis for optimal utilization of imaging techniques that allow preoperative localization of parathyroid adenomas.