title: Mammary Analog Secretory Carcinoma (MASC) Involving the Thyroid Gland: A Report of the First 3 Cases.
abstract: Salivary gland-type tumors have been rarely described in the thyroid gland. Mammary Analog Secretory Carcinoma (MASC) is a recently defined type of salivary gland carcinoma characterized by a t(12;15)(p13;q25) resulting in an ETV6-NTRK3 fusion gene. We report 3 cases of MASC involving the thyroid gland without clinical evidence of a salivary gland or breast primary; the clinico-pathologic characteristics are reviewed. Assessment for rearrangement of the ETV6 (12p13) locus was conducted by fluorescence in situ hybridization (FISH) on representative FFPE sections using an ETV6 break apart probe (Abbott Molecular, Des Plaines, IL, USA). The patients were two females (52 and 55 years-old) and 1 male (74 years-old). The tumors were poorly circumscribed solid white tan nodules involving the thyroid. Histologically, they were invasive and showed solid, microcystic, cribriform, and tubular growth patterns composed of variably bland polygonal eosinophilic cells with vesicular nuclear chromatin and conspicuous nucleoli. All three cases showed metastasis to lymph nodes; one case showed lateral neck involvement. The tumor cells were positive for S100 and mammaglobin. GATA-3 and PAX-8 were positive in 2 cases, one of which only focally so. All three cases were negative for TTF-1 and thyroglobulin. Rearrangement of the ETV6 locus was confirmed in all cases and a diagnosis of MASC rendered for each case. A site of origin distinct from the thyroid gland was not identified, with a median follow up of 24 months. MASC may rarely involve the thyroid gland. The origin of these lesions is unknown; while an origin from ectopic salivary gland-type cells is entertained, a metastatic origin from an occult primary cannot be definitively excluded at this time. Given the histologic (follicular-like microcystic pattern with colloid-like secretions and papillary pattern), immunophenotypic (PAX-8), and even molecular overlap, MASC can be mistaken for papillary thyroid carcinoma and should be considered in the differential diagnosis of a thyroid mass.
authors.affiliation: Department of Pathology and Cell Biology, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Dettloff
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Pittsburgh Medical Center, Pittsburgh, PA, 15213, USA.
authors.forename: Raja R
authors.initials: RR
authors.lastname: Seethala
authors.affiliation: Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, USA.
authors.forename: Todd M
authors.initials: TM
authors.lastname: Stevens
authors.affiliation: Department of Pathology and Anatomical Sciences, University at Buffalo The State University of New York, Buffalo, NY, USA.|Department of Pathology, Erie County Medical Center, Buffalo, NY, USA.
authors.forename: Margaret
authors.initials: M
authors.lastname: Brandwein-Gensler
authors.affiliation: Department of Anatomic Pathology, Head and Neck Pathology and Cytopathology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA.|Department of Oncologic Sciences, Pathology and Cell Biology, Morsani College of Medicine, University of South Florida, 12902 Magnolia Drive, Tampa, FL, 33612, USA.
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Centeno
authors.affiliation: Head and Neck Oncology Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA.
authors.forename: Kristen
authors.initials: K
authors.lastname: Otto
authors.affiliation: Departments of Pathology/Microbiology and Pediatrics and Orthopaedic Surgery, Nebraska Medical Center, Omaha, NE, 68198-3135, USA.
authors.forename: Julia A
authors.initials: JA
authors.lastname: Bridge
authors.affiliation: Departments of Pathology, Oncology, and Otolaryngology-Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, 21231, USA.
authors.forename: Justin A
authors.initials: JA
authors.lastname: Bishop
authors.affiliation: Department of Anatomic Pathology, Head and Neck Pathology and Cytopathology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA. Marino.Leon@Moffitt.org.|Head and Neck Oncology Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33612, USA. Marino.Leon@Moffitt.org.|Department of Oncologic Sciences, Pathology and Cell Biology, Morsani College of Medicine, University of South Florida, 12902 Magnolia Drive, Tampa, FL, 33612, USA. Marino.Leon@Moffitt.org.
authors.forename: Marino E
authors.initials: ME
authors.lastname: Leon
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D000069295:Mammary Analogue Secretory Carcinoma / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D008875:Middle Aged; D015514:Oncogene Proteins, Fusion / Q000235:genetics; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology*; D020812:Receptor, trkC; D000097764:ETS Translocation Variant 6 Protein
chemical_list: D015514:Oncogene Proteins, Fusion; C484319:ETV6-NTRK3 fusion protein, human; D020812:Receptor, trkC; D000097764:ETS Translocation Variant 6 Protein
keywords: Adenocarcinomas; ETV6-NTRK3; Mammary analog secretory carcinoma; Salivary gland-type carcinomas; Thyroid