Nucleolar organizer regions in normal, hyperplastic and neoplastic parathyroid glands.

Using a one-stage silver staining technique, nucleolar organizer regions (AgNORs) were studied in paraffin sections of parathyroid glands (and in two lymph node metastases) from patients operated upon because of hyperparathyroidism or thyroid disease. The parathyroids were microscopically differentiated into normal, hyperplastic, adenomatous and carcinomatous glands. AgNORs were observed as distinct black dots of varying size and somewhat varying configuration in the nuclei of all glands. The mean number of AgNORs in the hyperplastic and adenomatous glands was not significantly different from that in the normal glands, whereas the carcinomatous glands exhibited significantly increased mean AgNOR number. No evidence was obtained for a role of AgNOR counting in the differentiation between normal and hyperplastic or adenomatous parathyroids, but the results suggest a potential role of enumeration of AgNORs in the discrimination between benign and malignant parathyroid neoplasms.