Primary paraganglioma of the parathyroid: a case report and clinicopathologic review.

Paragangliomas are relatively uncommon neoplasms that arise in adrenal and extra-adrenal paraganglia of the autonomic nervous system. Parasympathetic paraganglioma develop predominantly in the head and neck. It is exceedingly uncommon to develop a primary intraparathyroid paraganglioma. There is only a single case report in the English literature. The information from the single previous case report (Medline 1960-2009) was combined with this case report. Our patient was a 69 year old woman who presented with a thyroid gland mass, with extension into the substernal space. The patient had a history of renal cell carcinoma removed 18 months before. At surgery, a thyroid lobectomy and a parathyroidectomy were performed. The parathyroid tissue showed a very well defined zellballen arrangement of paraganglion cells within the parenchyma of the parathyroid gland. The cells had ample basophilic, granular cytoplasm. The nuclei were generally round to oval with 'salt-and-pepper' nuclear chromatin distribution. There was a richly vascularized stroma. Mitotic figures, necrosis, invasive growth, and profound nuclear pleomorphism were absent. The neoplastic cells were strongly and diffusely immunoreactive with chromogranin, synaptophysin, CD56, and focally with cyclin-D1. The paraganglioma showed a delicate S-100 protein positive supporting sustentacular framework. Keratin, CD10, PTH, calcitonin and RCC markers were negative. The patient showed no stigmata of Multiple Endocrine Neoplasia (MEN) and has no paraganglioma in any other anatomic site. She is alive without any additional findings 12 months after surgery. Isolated paraganglioma within the parathyroid is rare, and should be separated from parathyroid adenoma, hyperplasia or metastatic disease to assure appropriate management.