PIK3CA and adenoma: Although established, oncogenic PIK3CA hotspot mutations are significantly more common in parathyroid carcinoma (approximately 10%) in comparison to parathyroid adenomas (1%; Fisher exact test, p = 0.0019), adenomas are roughly 100 to 200 times more common than carcinoma, decreasing the positive predictive value of PIK3CA mutational testing in unselected cases.