Multicellular origin of parathyroid "adenomas".

Most cases of primary hyperparathyroidism are associated with enlargement of a single gland (i.e., an "adenoma") or with chief-cell hyperplasia, but there is controversy about the relative frequency of each of these entities. It has even been postulated that adenomas do not arise spontaneously, bu- result from prolonged hyperplasia in response to unknown stimuli. We studied four parathyroid adenomas from three women with heterozygosity (GdB/GdA) for the X-chromosome-linked enzyme, glucose-6-phosphate dehydrogenase, to determine the number of cells from which the growths arise. Unicellular origin would be compatible with a rare oncogenic event, whereas multicellular origin might be seen with hyperplasia. Both B and A isoenzymes were found in each "adenoma" in proportions similar to those observed in normal tissues, indicating that the lesions have multicellular origin. Thus, parathyroid hyperplasia and adenomas, which at best are difficult to distinguish from one another pathologically, may also be similar biologically.