Table 4.

Immunohistochemical profiles for common differential diagnoses of metastatic cancer in the thyroid versus primary thyroid neoplasms.

Metastatic in Thyroid with Primary Tumour From	Main Differential Diagnoses	Usual Immunochemical Profiles
		Positive in Metastatic Primary Tumour	Positive in Thyroid, Primary Thyroid Neoplasms, or Parathyroid
Renal cell carcinoma	Oncocytic (Hürthle) cell neoplasm, follicular neoplasm with clear cell component	CAIX, CD10	TTF-1, thyroglobulin
Lung carcinoma (adenocarcinoma)	Anaplastic follicular cell-derived thyroid carcinoma	Napsin	PAX-8
Breast carcinoma	Follicular thyroid neoplasms, parathyroid neoplasms	GATA-3, oestrogen receptor, progesterone receptor	TTF-1, thyroglobulin
	Parathyroid neoplasms	GATA-3, oestrogen receptor, progesterone receptor	Parathyroid hormone
Colorectal adenocarcinoma	Anaplastic follicular cell-derived thyroid carcinoma	SATB2	TTF-1, thyroglobulin
Malignant melanoma	Papillary thyroid carcinoma, anaplastic follicular cell-derived thyroid carcinoma	S-100, HMB-45, Sox-10	TTF-1, thyroglobulin,
	Medullary thyroid carcinoma	S-100, HMB-45, Sox-10	Calcitonin
Neuroendocrine tumour	Medullary thyroid carcinoma	Cytokeratins	Calcitonin
	Paraganglioma in thyroid	Cytokeratins	S-100 (sustentacular cells), tyrosine hydroxylase, GATA3
Squamous cell carcinoma of the head and neck	Anaplastic follicular cell-derived thyroid carcinoma, squamous subtype	-	PAX-8, TTF-1, thyroglobulin (only in a portion of cases)