title: Metastasis of colon cancer to the thyroid gland: a case diagnosed on fine-needle aspirate by a combined cytological, immunocytochemical, and molecular approach.
abstract: Fine-needle aspiration (FNA) with cytological evaluation reliably diagnoses primary and secondary thyroid neoplasms. However, identifying the primary origin of a metastatic process involving the thyroid gland is challenging. In particular, metastasis of colon cancer to the thyroid gland is very rare. In this case report, a right lobe solid thyroid nodule in a 66-year-old male was aspirated. FNA cytology showed necrosis and atypical tall columnar cells; since, the patient at age 60 had undergone surgery for a sigmoid-rectal cancer metastasizing to the liver and subsequently to the lung, a suspicion of metastasis from colon cancer was raised. This was corroborated by cell-block immunocytochemistry showing a cytokeratin (CK) 7 negative/CK20-positive staining pattern; thyreoglobulin and TTF-1 were both negative. Since KRAS codon 12/13 mutations frequently occur in colon cancer, whereas they are extremely uncommon in primary thyroid tumors, DNA was extracted from the aspirated cells, and KRAS mutational analysis was carried out. The codon 12 G12D mutation was found; the same mutation was evident in the primary cancer of the colon and in its liver and lung metastasis. Thus, a combined cytological, immunocytochemical and molecular approach unquestionably correlated metastatic adenocarcinoma cells aspirated from the thyroid to a colo-rectal origin.
authors.affiliation: Dipartimento di Scienze Biomorfologiche e Funzionali, Università di Napoli Federico II, Naples, Italy.
authors.forename: Immacolata
authors.initials: I
authors.lastname: Cozzolino
authors.forename: Umberto
authors.initials: U
authors.lastname: Malapelle
authors.forename: Chiara
authors.initials: C
authors.lastname: Carlomagno
authors.forename: Lucio
authors.initials: L
authors.lastname: Palombini
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Troncone
mesh_terms: D001483:Base Sequence; D044963:Biopsy, Fine-Needle; D003110:Colonic Neoplasms / Q000235:genetics / Q000473:pathology*; D003581:Cytodiagnosis; D004252:DNA Mutational Analysis; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D008969:Molecular Sequence Data; D011518:Proto-Oncogene Proteins / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras); D013961:Thyroid Gland / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000556:secondary*; D018631:ras Proteins / Q000235:genetics
chemical_list: C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins