title: Tumor-to-tumor metastasis to a thyroid follicular adenoma as the initial presentation of a colonic adenocarcinoma.
abstract: The incidence of thyroid involvement by metastatic disease from distant organs ranges from an average of 3.1% in surgical series to 5.3% in autopsy series. However, the metastasis of one tumor into another (traditionally referred to as 'tumor-to-tumor metastasis') is distinctly uncommon. Typically, they are identified as new manifestations or necropsy findings of a known, pre-existing donor tumor. Herein is described the case of a 59-year-old woman whose thyroid nodule (a follicular adenoma) was resected and found to contain foci of a well-differentiated adenocarcinoma with a morphologic and immunohistochemical profile consistent with origination from the lower gastrointestinal tract. Subsequent diagnostic work-up revealed a sigmoid colon tumor with metastases to the liver. This is, to the authors' knowledge, the first reported example of a colon adenocarcinoma whose initial clinical manifestation was a metastasis to a thyroid neoplasm and only the third reported example of a colonic adenocarcinoma metastatic to a thyroid tumor. In a review of previously reported examples of tumor-to-tumor metastases involving a thyroid neoplasm as the recipient, the following features were present in the majority: (i) multifocality of the metastatic tumor aggregates; (ii) a total lack of, or only minimal amounts of reaction (desmoplastic, inflammatory or myxoid) of the recipient tumor to the metastatic deposits; and (iii) retention of the histopathologic characteristics of the donor tumor in the metastatic deposits. In general, strikingly divergent morphologic features in an otherwise typical thyroid neoplasm should elicit a differential diagnosis that takes into consideration the possibility of metastasis.
authors.affiliation: Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06504, USA. oluwolefadare@yahoo.com
authors.forename: Oluwole
authors.initials: O
authors.lastname: Fadare
authors.forename: Vinita
authors.initials: V
authors.lastname: Parkash
authors.forename: Paul N
authors.initials: PN
authors.lastname: Fiedler
authors.forename: Adam B
authors.initials: AB
authors.lastname: Mayerson
authors.forename: Bolanle
authors.initials: B
authors.lastname: Asiyanbola
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000556:secondary*; D000236:Adenoma / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D000970:Antineoplastic Agents / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000378:metabolism; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000378:metabolism / Q000556:secondary; D008875:Middle Aged; D009367:Neoplasm Staging; D009378:Neoplasms, Multiple Primary; D013964:Thyroid Neoplasms / Q000378:metabolism / Q000556:secondary* / Q000601:surgery; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor