Carcinoma of the parathyroid gland. A light and electronmicroscopic study.

The morphological features of a functional parathyroid carcinoma in a 34-year-old female are presented. The case was unique in the high frequency of mitotic figures permitting a tentative diagnosis of malignancy already on frozen sections. The parathyroid nature of the lesion was established ultrastructurally by demonstration of secretory granules, glycogen particles and lipid material within the cytoplasm. Also noteworthy was the presence of annulate lamellae, denoting rapidly growing tissue. Few examples of this lesion are at hand, and ultrastructural studies which provide valuable information regarding the site of origin, have previously been recorded in only 6 publications.