title: Molecular Characterization of an Endometrial Endometrioid Adenocarcinoma Metastatic to a Thyroid Hürthle Cell Adenoma Showing Cancerization of Follicles.
abstract: Tumor-to-tumor metastasis is rare. Herein, we present a unique case of endometrial endometrioid adenocarcinoma metastatic to a thyroid Hürthle cell adenoma 9 years after initial diagnosis. On histologic examination of the thyroid, the malignant endometrioid glands and single cells (donor tumor) were dispersed within the Hürthle cell adenoma (recipient tumor). In several sections of the adenoma with still preserved microfollicular architecture, malignant endometrial adenocarcinoma cells were admixed within oncocytic adenomatous epithelium (so-called "cancerization of the follicles"). This unusual phenomenon, to our knowledge, is a novel finding in the thyroid gland. Immunohistochemistry, subsequently elicited clinical history, and morphologic comparison of the tumor in the thyroid to the primary endometrial tumor confirmed the origin of the donor tumor cells. Molecular analysis of both the metastatic and primary endometrial tumors demonstrated PIK3CA and PTEN mutations in both tumors, as is characteristic of well-differentiated endometrioid tumors of the endometrium. Amplification of chromosome 1q was detected in both sites; however, only the metastatic tumor showed loss of chromosomes 2, 9, and 22. The morphologic differential diagnosis of metastatic endometrioid adenocarcinoma in the thyroid includes columnar cell variant of papillary thyroid carcinoma (CCVPTC) arising in a preexisting adenoma, endocrine glandular atypia within an adenoma, and metastasis from other anatomic sites. Histomorphologic differences among these entities may be subtle; therefore, knowledge of and morphologic comparison with prior malignancies and immunohistochemistry can be helpful in rendering the correct diagnosis.
authors.affiliation: Department of Pathology, Massachusetts General Hospital, Boston, MA, 02114, USA.|Harvard Medical School, Boston, MA, 02114, USA.
authors.forename: Amir H
authors.initials: AH
authors.lastname: Afrogheh
authors.affiliation: Department of Pathology, Brigham & Women's Hospital, Boston, MA, 02115, USA.|Harvard Medical School, Boston, MA, 02114, USA.
authors.forename: Emily
authors.initials: E
authors.lastname: Meserve
authors.affiliation: Department of Pathology, Massachusetts General Hospital, Boston, MA, 02114, USA.|Harvard Medical School, Boston, MA, 02114, USA.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Sadow
authors.affiliation: Department of Surgical Oncology, Massachusetts General Hospital, Boston, MA, 02114, USA.|Harvard Medical School, Boston, MA, 02114, USA.
authors.forename: Antonia E
authors.initials: AE
authors.lastname: Stephen
authors.affiliation: Department of Pathology, Massachusetts General Hospital, Boston, MA, 02114, USA.|Harvard Medical School, Boston, MA, 02114, USA.
authors.forename: Vânia
authors.initials: V
authors.lastname: Nosé
authors.affiliation: Department of Medical Oncology, Dana Farber Cancer Institute, Boston, MA, 02115, USA.|Harvard Medical School, Boston, MA, 02114, USA.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Berlin
authors.affiliation: Department of Pathology, Massachusetts General Hospital, Boston, MA, 02114, USA. wfaquin@partners.org.|Harvard Medical School, Boston, MA, 02114, USA. wfaquin@partners.org.|Pathology Service, WRN219, Massachusetts General Hospital, 55 Fruit Street, Boston, MA, 02114, USA. wfaquin@partners.org.
authors.forename: William C
authors.initials: WC
authors.lastname: Faquin
mesh_terms: D018249:Adenoma, Oxyphilic / Q000473:pathology*; D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis; D044963:Biopsy, Fine-Needle; D018269:Carcinoma, Endometrioid / Q000556:secondary*; D016889:Endometrial Neoplasms / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D009378:Neoplasms, Multiple Primary / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000473:pathology / Q000556:secondary*
chemical_list: D014408:Biomarkers, Tumor
keywords: Cancerization of follicles; Columnar cell variant of papillary thyroid carcinoma; Endometrial endometrioid adenocarcinoma; Fine-needle aspiration biopsy; Hürthle cell adenoma; Thyroid; Tumor-to-tumor metastasis