A rare case of a patient with multiple endocrine neoplasia type 2 (MEN2) with medullary thyroid carcinoma
(MTC) metastasizing to adrenal pheochromocytoma was reported in China.

“The similar neuroendocrine histological appearance of pheochromocytoma and MTC made the pathological diagnosis of a metastatic MTC difficult, especially when the metastatic foci was very limited,” said the authors of the report published in the Asian Journal of Surgery.

The patient, a 30-year-old male, underwent thyroidectomy after presenting with a suspicious mass in 2019. Histopathological analysis confirmed the diagnosis of MTC with C cell hyperplasia.


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During follow-up, his levels of carcinoembryonic antigen (CEA), calcitonin, adrenaline, and noradrenaline increased. Imaging evaluation suggested systemic metastasis and pheochromocytoma in the bilateral adrenal gland, so the patient underwent left adrenalectomy.

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Microscopic evaluation of the specimen revealed classic morphological features of pheochromocytoma, as well as a small nest pattern of proliferative short spindle cells with clear to light-acidophilic cytoplasm.

The diagnosis of pheochromocytoma was further confirmed by the strongly positive staining of chromogranin A (CgA), synaptophysin (SYN), CD56, and GATA binding protein 3 (GATA3). Moreover, the foci tumor cells in pheochromocytoma expressed thyroid transcription factor 1 (TTF1), cytokeratin, calcitonin, and CEA.

Altogether, the findings suggested tumor-to-tumor metastasis in a patient with MEN2A, a rare autosomal-dominant hereditary cancer syndrome. A C634Y germline mutation was identified during RET gene analysis.

Examining the Genetics of Sporadic and Familial Medullary Thyroid Carcinoma

The analysis of GATA3, TTF1 and cytokeratin could be essential to identify metastasis of MTC in pheochromocytomas, the authors said. Their similar neuroendocrine histological appearance compromises the utility of neuroendocrine markers, such as CgA, SYN, and CD56, in their distinction. In addition, calcitonin may also be expressed by some pheochromocytomas and other neuroendocrine tumors.

Reference

Tuo Y-L, Xie J. MEN2A syndrome presenting as medullary thyroid cancer metastasis to pheochromocytoma. Asian J Surg. Published online March 9, 2022. doi:10.1016/j.asjsur.2022.01.078