Parathyroid : Chief Cell Hyperplasia

Chief cell hyperplasia may be primary or secondary to impaired renal function. Primary chief cell hyperplasia is seen in multiple endocrine neoplasia (MEN) types I, 2A and 4. Patients with MEN 2B have normal parathyroids during childhood and show only minimal chief cell hyperplasia in adulthood.

In a typical case of primary chief cell hyperplasia, all four parathyroid glands are enlarged. The upper glands tend to be larger than the lower ones. In some cases, one gland is considerably larger than the others and may be mistaken for an adenoma. The glands may also appear normal grossly but show clear-cut features of hyperplasia on histologic examination.