Unusual manifestation of parathyroid carcinoma in the setting of papillary thyroid cancer.

Objective: To describe a rare manifestation of parathyroid carcinoma in association with papillary thyroid carcinoma.

Methods: We describe the clinical history, findings on physical examination, results of laboratory studies, imaging findings, and histopathologic features of a woman with 2 previously palpable thyroid nodules and mild hypercalcemia.

Results: A 79-year-old woman presented to our endocrinology clinic for reevaluation of 2 thyroid nodules and long-standing hyperparathyroidism. She initially had undergone assessment 6 years previously, at which time an intact parathyroid hormone level was 89 pg/mL (reference range, 10 to 69) and the serum calcium concentration was 10.4 mg/dL (reference range, 8.2 to 10.2) in conjunction with normal alkaline phosphatase, creatinine, and 25-hydroxyvitamin D levels. Subsequently, she was found to have multifocal papillary thyroid cancer in the right thyroid lobe and a 5-cm parathyroid carcinoma in the left side.

Conclusions: Synchronous parathyroid and thyroid carcinomas are extremely rare. To our knowledge, our current case is the first documented patient with parathyroid carcinoma who had a clinical presentation consistent with longstanding mild adenoma in addition to synchronous papillary thyroid carcinoma.