The normal parathyroid and the borderline with early hyperplasia: a light microscopic study.

The light microscopical appearance of the normal parathyroid gland based on an autopsy study of 138 glands from 38 adults without evidence of hyperparathyroidism, is described. It differs from earlier descriptions in that we found less adipose tissue in the glands of many normal adults than had been reported. This observation is in keeping with several other recent reports. Other features of the normal gland are also described. This study suggests that at times, a distinction between normal and early hyperplasia cannot be made, especially if the distinction is based solely on the amount of stromal adipose tissue present. Histological features which appear to indicate abnormality are cytological atypia, chief cell nodularity and diminished intracytoplasmic lipid. A gland which is equivocally enlarged but which has minimal stromal adipose tissue and one or more of the above features is most likely to be abnormal.