Table 1. Immunohistochemical Analyses of the Core Biopsy and Thyroidectomy.

Specimen stain	Marker	Core biopsy	Thyroidectomy
Thyroglobulin	Follicular cell		+
TTF-1	Follicular cell		+
Calcitonin	Parafollicular cell	-	-
CEA	MTC		-
Congo red	MTC (amyloid)		-
Synaptophysin	NET	+	+
Chromogranin A	NET		+

TTF-1, thyroid transcription factor-1; CEA, carcinoembryonic antigen; MTC, medullary thyroid carcinoma; NET, neuroendocrine tumor.