title: Extra-osseous Ewing sarcoma of the thyroid gland mimicking lymphoma recurrence: a case report.
abstract: Extra-osseous Ewing sarcomas/peripheral primitive neuroectodermal tumors (EOES/pPNETs) are high-grade malignant tumors found in various organs, such as the lung, skin, intestine, kidney and female genital tract; however, to the best of our knowledge, only two cases have previously been identified in the thyroid gland. We describe a case of primary EOES/PNET of the thyroid gland in a 66-year-old man with a previous history of large B cell lymphoma. During a routine follow-up examination, the patient underwent an ultrasound cervical scan showing a solid nodule of the left thyroid lobe. The fine-needle aspiration biopsy of the nodule suggested a neuroendocrine tumor. Histological and immunohistochemical examination of the surgical specimen supported a diagnosis of EOES/PNET, which was further confirmed by the demonstration of EWSR1 gene translocation by means of fluorescent in situ hybridization and by the detection of glycogen particles and neurosecretory granules by means of electron microscopy. Total body computed tomography and magnetic resonance imaging excluded the involvement of other sites, and therefore a diagnosis of primary EOES/PNET of the thyroid gland was made.This paper also discusses the main differential diagnoses, including lymphoma recurrence, other small round cell tumors (primary or metastatic), and a thyroid localization of an EWS/PNET from another organ.
authors.affiliation: Dipartimento di Medicina della Salute, Facoltà di Medicina e Chirurgia, Università del Piemonte Orientale Amedeo Avogadro, Novara, Italy. elena.maldi@gmail.com
authors.forename: Elena
authors.initials: E
authors.lastname: Maldi
authors.forename: Guido
authors.initials: G
authors.lastname: Monga
authors.forename: Davide
authors.initials: D
authors.lastname: Rossi
authors.forename: Antonella
authors.initials: A
authors.lastname: Tosoni
authors.forename: Rosanna
authors.initials: R
authors.lastname: Mezzapelle
authors.forename: Renzo
authors.initials: R
authors.lastname: Boldorini
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism; D001707:Biopsy, Needle; D002148:Calmodulin-Binding Proteins / Q000235:genetics; D004273:DNA, Neoplasm / Q000032:analysis; D003937:Diagnosis, Differential; D006003:Glycogen / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D033162:Incidental Findings; D008198:Lymph Nodes / Q000473:pathology; D016403:Lymphoma, Large B-Cell, Diffuse / Q000175:diagnosis*; D008297:Male; D009364:Neoplasm Recurrence, Local; D018241:Neuroectodermal Tumors, Primitive, Peripheral / Q000235:genetics / Q000378:metabolism / Q000556:secondary*; D034802:RNA-Binding Protein EWS; D016601:RNA-Binding Proteins / Q000235:genetics; D012512:Sarcoma, Ewing / Q000235:genetics / Q000556:secondary*; D022142:Secretory Vesicles / Q000378:metabolism / Q000648:ultrastructure; D013964:Thyroid Neoplasms / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism / Q000473:pathology* / Q000556:secondary; D014178:Translocation, Genetic
chemical_list: D014408:Biomarkers, Tumor; D002148:Calmodulin-Binding Proteins; D004273:DNA, Neoplasm; C500986:EWSR1 protein, human; D034802:RNA-Binding Protein EWS; D016601:RNA-Binding Proteins; D006003:Glycogen