The role of the pathologist in the surgical treatment of hyperparathyroidism.

Appropriately extensive surgical treatment of hyperparathyroidism depends upon accurate assessment of the extent of disease. We have believed that such assessement is the responsibility of the surgeon because at random biopsy with light microscopy the pathologist may not be able to differentiate adenoma from hyperplasia or even normal from abnormal glands. To test this hypothesis, three pathologists reviewed 50 unlabelled slides of parathyroid tissue and attempted to correlate them with clinical diagnoses which were based upon widely accepted criteria. They were asked to identify each slide as adenoma or hyperplasia, or both, or normal using whatever criteria they wished. A specific diagnosis of adenoma was correct in 35 and 83 per cent of interpretations and of hyperplasia in 38 and 60 per cent of interpretations. The less specific diagnosis of adenoma or hyperplasia (that is, abnormal tissue) was correct in 78 to 100 per cent. A diagnosis of normal was correct in 71 to 78 per cent. Adenoma was most likely confused with hyperplasia; hyperplasia was equally mistaken for adenoma or normal. We conclude that with random, subtotal specimens taken at biopsy (simulating intraoperative conditions) differentiation of adenoma from hyperplasia of the parathyroid gland is poor. Differentiation of normal from abnormal parathyroid tissue also is unreliable. Because the consequences of misdiagnosis are severe, pathologists should not be asked to make specific diagnoses intraoperatively but only to distinguish the parathyroid tissue from the nonparathyroid tissue.