Paraganglioma‐like medullary thyroid carcinoma: A case report and literature review

Abstract

Medullary thyroid carcinoma (MTC) accounts for 3%‐5% of all thyroid malignancies. Most MTC can be diagnosed by their typical cytologic and histologic morphology and immunohistochemical features. However, some rare variants of MTC may pose diagnostic difficulties on both cytology and histology. Paraganglioma‐like MTC (PLMTC) is a rare, but widely recognized variant of MTC. PLMTC is known to share morphological and architectural similarities with paraganglioma, hyalinizing trabecular tumor, and carcinomas of thyroid follicular cell origin, such as follicular carcinoma and follicular variant of papillary thyroid carcinoma. The combination of clinicopathologic features and a battery of immunohistochemical markers is essential for making a correct diagnosis. Herein, we report one case of PLMTC with both cytologic and histologic features and review the clinicopathologic features of previously reported cases.

Thyroid Paraganglioma With Medullary Carcinoma: A Unique Combination in a Patient in Association With Multiple Endocrine Neoplasia Type 2B Syndrome With Prolonged Survival

“…The differential diagnosis includes nesting-pattern-forming neoplasms, such as MTC, hyalinizing trabecular tumor, and metastases of neuroendocrine carcinomas to thyroid [ 1 ]. In particular, the PGL-like variant of MTC, rarely reported in the literature, mimics the typical “Zellballen” pattern of PGL and may also show sustentacular cells surrounding the cell nests [ 8 , 9 ]. The diagnosis of MTC is established by positive immunostains for calcitonin, CEA, and cytokeratins.…”

“…The diagnosis of MTC is established by positive immunostains for calcitonin, CEA, and cytokeratins. In clinical terms, elevated serum calcitonin further supports the diagnosis [ 8 , 9 ]. In our patient, the MTC consisting mostly of spindle cells was distinct from PRG.…”