Nonfunctioning parathyroid carcinoma associated with parathyromatosis. A case report.

We report on the case of a 39-year old man who underwent a thyroidectomy and a parathyroidectomy with misdiagnosed medullary carcinoma of the thyroid in 2013. During the operation the thyroid gland and parathyroid glands were artificially damaged due to the complicated surgical access to the glands because of the obesity of the patient as well as the deep placement of the enlarged parathyroid glands. Three years later, the neck ultrasound showed bilateral nodules on the neck, suspected to be metastases of the medullary carcinoma. Microscopically, the nodules were found to be focuses of parathyromatosis, and there was also an infiltrating carcinoma. This lesion was reclassified after clinico-pathological correlation and immunohistochemical examination as nonfunctioning parathyroid carcinoma. This article discusses morphological and immunohistochemical features of parathyromatosis and parathyroid carcinoma and its separation from lesions with which it may be misdiagnosed.