TTF-1 positive atypical carcinoid of the epiglottis mimicking medullary thyroid carcinoma

Introduction

Primary neuroendocrine tumors of the larynx are a very rare disease comprising only ~0.6 % of laryngeal neoplasms [1]. According to the WHO [2], neuroendocrine tumors of the larynx are subdivided into paragangliomas, typical carcinoids, atypical carcinoids, small cell carcinomas (neuroendocrine type) and combined small cell carcinomas (neuroendocrine type). Atypical carcinoids are the most frequent neuroendocrine tumors of the larynx and are rather aggressive tumors with frequent lymph node metastases. They usually occur in older men with a history of heavy smoking and have a 5-year survival rate of only 50 % [3]. Immunohistochemistry is usually positive for chromogranin as well as for synaptophysin and shows a frequent overexpression of calcitonin [2]. Therefore, atypical carcinoids can be confounded with metastases or ectopic manifestations of the far more frequent medullary thyroid carcinoma (MTC) for which calcitonin is the most specific marker. MTCs show positivity for chromogranin and synaptophysin alike [2]. They account for 1–2 % of all thyroid carcinoma and occur either sporadically or hereditary, often between the fifth or sixth decade of life. Prognosis depends on tumor size and the presence of lymph node or distant metastases. Therefore, 10-year survival rates range between 100–71 % in local disease and are only 21 % in advanced disease setting [4].

• References

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