Calcitonin-negative neuroendocrine tumor of the thyroid with metastasis to liver-rare presentation of an unusual tumor: A case report and review of literature

Metastatic Neuroendocrine Neoplasms to the Pancreas: Two Unusual Cases and a Review of the Literature

“…22,28 In addition, calcitonin-negative medullary thyroid carcinomas have been reported, although they are extremely rare. 25 The cytomorphological features, including plasmacytoid cells with finely stippled to slightly clumped chromatin, are similar to those seen in other neuroendocrine tumors. Amyloid, when present, can be a helpful clue.…”

“…Immunohistochemical staining for TTF1, when positive, favors pulmonary over gastrointestinal origin for carcinoid tumors, however not all pulmonary primary carcinoid tumors stain positively with TTF1, and gastrointestinal carcinoid tumors with TTF1 positivity, although weak and focal, have rarely been reported. 25,38 In patient 2, the cytomorphological features of the neoplastic cells, including uniform nuclei, indiscernible nucleoli, eosinophilic cytoplasm, and finely stippled to slightly clumped chromatin, were suggestive of a neuroendocrine neoplasm but not specific for a primary origin. The neoplastic cells were immunoreactive for keratin AE1/AE3, synaptophysin, chromogranin, INSM1, and TTF1 but negative for ISL1 and CDX2.…”

“…21,23,24 medullary thyroid carcinoma is more aggressive and has a poorer prognosis than well-differentiated thyroid carcinomas. 21,25 In the 5th edition of the WHO Classification of Tumors , it is recommended to report the mitotic activity and histological tumor grade of medullary thyroid carcinoma according to the International Collaboration on Cancer Reporting guidelines. 24,26 Since medullary thyroid carcinoma have the phenotype of thyroid C-cells, the neoplastic C-cells nearly always secrete calcitonin, which makes serum calcitonin a useful marker for the clinical diagnosis and prognosis of medullary thyroid carcinoma.…”

Neuroendocrine metastasis to the thyroid from unknown primary and extrathyroidal disease response to peptide receptor radionuclide therapy

“…The typical treatment for NET metastasis to the thyroid includes total thyroidectomy, however, surgical resection is not recommended for tumors with poor prognosis [16] . The benefit of PRRT in these metastatic lesions has not been well established and to our knowledge, has been reported only once in the literature [8] .…”

Calcitonin negative medullary thyroid cancer in ectopic thyroid tissue: a rare diagnosis in an unusual location

“…Positivity of TFF-1, a transcription factor regulating the expression of thyroid-specific genes could be highly suggestive of a thyroid tumour and is often detected in both MTC and CNMTC. 11 A recent literature review compared results from 51 cases with CNMTC. This revealed on staining that almost half of the cases showed positivity for CT and CEA, and that 41 out of 43 tested cases showed positivity of CgA.…”