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Abstract
In the thyroid, primary neuroendocrine tumors encompass medullary thyroid carcinoma (MTC) and, rarely, other tumors such as paragangliomas. MTCs are derived from C-cells and express calcitonin and neuroendocrine markers. Besides classic MTC, some reports have documented thyroid neuroendocrine tumors, which show no calcitonin expression and raise difficult diagnostic problems. A 76-year-old man presented with a mass in the left thyroid with neither serological calcitonin elevation nor familial history. A thorough clinico-laboratorial study did not disclose any other mass elsewhere. A left hemithyroidectomy was performed, and the histological examination revealed a neuroendocrine carcinoma resembling a paraganglioma-like MTC displaying unequivocal signs of vascular invasion. Immunohistochemically, the tumor cells showed reactivity for chromogranin A, synaptophysin, thyroid transcription factor-1 (TTF-1), paired box gene 8 (PAX8), cytokeratins (AE1/AE3 and CK8/18), and calcitonin gene-related peptide (CGRP) and negativity for calcitonin, carcinoembryonic antigen, TTF-2, thyroperoxidase, and thyroglobulin. In situ hybridization showed that the tumor cells lacked expression for calcitonin and thyroglobulin mRNA. Genetic analysis did not disclose any RET mutation. A diagnosis of C-cell-derived primary neuroendocrine carcinoma of the thyroid without calcitonin expression was made, and the patient remains free of metastasis or recurrence 18 months after surgery.
References
| 1. |
Matias-Guiu, X, DeLellis, R, Moley, JF. Medullary thyroid carcinoma. In: DeLellis, RA, Lloyd, RV, Heitz, PU, Eng, C, eds. Pathology and Genetics of Tumours of Endocrine Organs. WHO Classification of Tumours. Lyon, France: IARC Press; 2004:86-91. Google Scholar |
| 2. |
LaGuette, J, Matias-Guiu, X, Rosai, J. Thyroid paraganglioma: a clinicopathologic and immunohistochemical study of three cases. Am J Surg Pathol. 1997;21:748-753. Google Scholar | Crossref | Medline | ISI |
| 3. |
González Poqqioli, N, López Amado, M, Pimentel, MT. Paraganglioma of the thyroid gland: a rare entity. Endocr Pathol. 2009;20:62-65. Google Scholar | Crossref | Medline | ISI |
| 4. |
Ikeda, T, Satoh, M, Azuma, K, Sawada, N, Mori, M. Medullary thyroid carcinoma with a paraganglioma-like pattern: a case report with ultrastructural and immunohistochemical studies. Arch Pathol Lab Med. 1998;122:555-558. Google Scholar | Medline | ISI |
| 5. |
Bockholm, M, Sheu, SY, Frilling, A, Molmenti, E, Schmid, KW, Broelsch, CE. Paraganglioma-like medullary thyroid carcinoma: a rare entity. Thyroid. 2005;15:1363-1367. Google Scholar | Crossref | Medline | ISI |
| 6. |
Schmid, KW, Ensinger, C. “Atypical” medullary thyroid carcinoma with little or no calcitonin expression. Virchows Arch. 1998;433:209-215. Google Scholar | Crossref | Medline | ISI |
| 7. |
Chernyavsky, VS, Farghani, S, Davidov, T. Calcitonin-negative neuroendocrine tumor of the thyroid: a distinct clinical entity. Thyroid. 2011;21:193-196. Google Scholar | Crossref | Medline | ISI |
| 8. |
Cameselle-Teijeiro, J, Menasce, LP, Yap, BK. Cribriform-morular variant of papillary thyroid carcinoma: molecular characterization of a case with neuroendocrine differentiation and aggressive behavior. Am J Clin Pathol. 2009;131:134-142. Google Scholar | Crossref | Medline | ISI |
| 9. |
Matias-Guiu, X, LaGuette, J, Puras-Gil, AM, Rosai, J. Metastatic neuroendocrine tumors to the thyroid gland mimicking medullary carcinoma: a pathologic and immunohistochemical study of six cases. Am J Surg Pathol. 1997;21:754-762. Google Scholar | Crossref | Medline | ISI |
| 10. |
Srodon, M, Westra, WH. Immunohistochemical staining for thyroid transcription factor-1: a helpful aid in discerning primary site of tumor origin in patients with brain metastases. Hum Pathol. 2002;33:642-645. Google Scholar | Crossref | Medline | ISI |
| 11. |
Russo, AF, Nelson, C, Roos, BA, Rosenfeld, MG. Differential regulation of the coexpressed calcitonin/α-CGRP and β- CGRP neuroendocrine genes. J Biol Chem. 1988;263:5-8. Google Scholar | Medline | ISI |
| 12. |
Williums, ED, Ponder, BJ, Craig, RK. Immunohistochemical study of calcitonin gene-related peptide in human medullary carcinoma and C cell hyperplasia. Clin Endocrinol. 1987;27:107-114. Google Scholar | Crossref | Medline | ISI |
| 13. |
Nonaka, D, Tang, Y, Chiriboga, L, Rivera, M, Ghossein, R. Diagnostic utility of thyroid transcription factors Pax8 and TTF-2 (FoxE1) in thyroid epithelial neoplasms. Mod Pathol. 2008;21:192-200. Google Scholar | Medline | ISI |
| 14. |
Zhang, P, Zuo, H, Nakamura, Y, Nakamura, M, Wakasa, T, Kakudo, K. Immunohistochemical analysis of thyroid-specific transcription factors in thyroid tumors. Pathol Int. 2006;56:240-245. Google Scholar | Crossref | Medline | ISI |
