Increased incidence of thyroid cancer in patients with primary hyperparathyroidism: a continuing dilemma.

A number of previous studies have reported a greater incidence of thyroid disease in patients with primary hyperparathyroidism (HPT) than in normal patients. However, few of these studies utilized controls, and most have dealt only with gross thyroid nodules and not with total histologic abnormalities. In order to clarify this problem, thyroid pathology was determined in each of 100 consecutive patients operated upon for HPT. Thyroid nodules were excised, but in addition, a random biopsy of the thyroid was performed in all cases. Patients in this group were matched by age, race, and sex with non-HPT autopsy controls. Histologic slides were reviewed by a single pathologist blinded to the patient's group. Data for the matched pairs were analyzed by the Sign test. There was no significant difference in the prevalence of colloid nodular disease between patients with HPT (45) and the autopsy control group (43, P = 0.2). There was also no significant difference in the prevalence of lymphocytic thyroiditis between HPT patients (24) and control (15, P = 0.07). There was likewise no significant difference in the prevalence of other benign thyroid gland diseases between the two groups. Only nonmedullary cancer of the thyroid was shown to be statistically more prevalent in HPT patients than in autopsy controls (7% vs 0%, respectively; P < 0.02). The major factor that accounts for the coexistence of benign thyroid lesions and HPT is that both are prevalent in middle-aged women.(ABSTRACT TRUNCATED AT 250 WORDS)