Secondary hyperparathyroidism: evidence for an association with papillary thyroid cancer.

The association between primary hyperparathyroidism and nonmedullary thyroid malignancies is well known. There is also, however, some evidence for an association between secondary hyperparathyroidism (SHPT) and thyroid cancer. We report three patients in whom invasive papillary thyroid carcinoma (PTC) was diagnosed before (one case) or at the time of (two cases) parathyroidectomy for SHPT. Three women (ages 23, 54, and 64 years) presented with bone pain and pruritus typical of SHPT. All three patients had biopsy-proven parathyroid bone disease and elevated parathormone levels (664, 1674, and 2051 pg/mL). All underwent subtotal parathyroidectomy and total thyroidectomy without complications. Pathology revealed diffuse parathyroid hyperplasia with multifocal invasive papillary thyroid carcinoma (two cases) and follicular variant of papillary thyroid carcinoma (one case). Two cases were associated with metastatic disease to local lymph nodes. The patients received adjuvant radioactive 131I, and remained tumor free 24 to 36 months after surgery with complete resolution of SHPT. We conclude: 1) PTC may accompany SHPT, 2) PTCs associated with SHPT may be locally aggressive although usually they are early tumors, 3) surgeons need to have an index of suspicion for thyroid tumor when operating on patients with SHPT, and 4) routine removal of the thymus as part of the operation for SHPT may have a secondary benefit in diagnosing PTC in the occasional patient.