Introduction: Parathyroid carcinoma (PC) is exceptional cause of primary hyperparathyroidism (PHPT). It has an estimated prevalence of 0.3 to 5.6% and is rarely associated with non-medullary thyroid cancer.
Observation: We report a case of parathyroid carcinoma resulting in a hyperparathyroidism and revealing a papillary thyroid carcinoma and emphasize on the management particularities of this entity. A 37-year-old woman, with prolactin secreting pituitary microadenoma, presented with asthenia and bone pain. Laboratory findings were consistent with PHPT. Neck ultrasonography showed a 3 cm nodule adjacent to the right thyroid lobe with no abnormalities in the thyroid gland. Parathyroid scintigraphy showed a right inferior parathyroid adenoma. Because of the patient age and the decreased renal function, surgical treatment was required. During the intra-operative neck exploration, a juxta-thyroid tumoral right mass was strongly adherent to the right infra-hyoid muscle and the recurrent laryngeal nerve. The frozen examination of the mass demonstrated malignancy features suggesting a poorly differentiated thyroid carcinoma. Thus, a total thyroidectomy with bilateral central neck dissection was carried out. Final histopathological examination showed a 3.5 cm PC infiltrating the thyroid gland with a papillary thyroid microcarcinoma of the left thyroid lobe. External radiotherapy of the neck, indicated for PC, was performed 1 month after surgery. A radioactive iodine therapy was used 6 months postoperatively.
Conclusion: Despite its rarity, PC is to bear in mind in case of PHPT. The association between PC and differentiated thyroid carcinoma is not to be ignored.