title: PNET with neuroendocrine differentiation of the lung: Report of an unusual entity.
abstract: Ewing's sarcoma/primitive neuroectodermal tumor (PNET) has been the subject of recent reports describing morphologic variants (adamantinoma-like, large cell, spindle cell, sclerosing, clear cell, and vascular-like) of the most classic form, as well as cases displaying unusual morphologic differentiation and atypical immunohistochemical features. We report a case of an uncommon lung tumor in a 20-year-old female, morphologically and molecularly consistent with an Ewing's sarcoma/PNET tumor with foci of squamous differentiation, and peculiar expression of vimentin, high-molecular-weight keratins, p63, synaptophysin, and chromogranin. This case raises a challenging differential diagnostic problem with therapeutic implications: Should the patient be treated following the protocols for Ewing's sarcoma/PNET tumors or as for lung carcinoma with neuroendocrine features? The patient we report here was treated with neoadjuvant chemotherapy for Ewing's sarcoma/PNET according to Euro Ewing 99 study protocol followed by surgery and has no evidence of disease 15 months after the initial diagnosis. This highlights the importance of achieving the correct diagnosis of these atypical tumors using all clinical, morphological, and ancillary methods available to allow for their correct and timely treatment.
authors.affiliation: Centro Hospitalar S João, Porto, Portugal Departamento de Patologia e Oncologia Médica da Faculdade de Medicina da Universidade do Porto, Porto, Portugal hbarroca@gmail.com.
authors.forename: Helena
authors.initials: H
authors.lastname: Barroca
authors.affiliation: Centro Hospitalar S João, Porto, Portugal Departamento de Patologia e Oncologia Médica da Faculdade de Medicina da Universidade do Porto, Porto, Portugal.
authors.forename: Conceição
authors.initials: C
authors.lastname: Souto Moura
authors.affiliation: Centro Hospitalar S João, Porto, Portugal Departamento de Patologia e Oncologia Médica da Faculdade de Medicina da Universidade do Porto, Porto, Portugal Instituto de Patologia e Imunologia Molecular da Universidade do Porto (IPATIMUP), Porto, Portugal.
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Lopes
authors.affiliation: Instituto Português de Oncologia do Porto e Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal.
authors.forename: Susana
authors.initials: S
authors.lastname: Lisboa
authors.affiliation: Instituto Português de Oncologia do Porto e Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal.
authors.forename: Manuel R
authors.initials: MR
authors.lastname: Teixeira
authors.affiliation: Centro Hospitalar S João, Porto, Portugal Departamento de Patologia e Oncologia Médica da Faculdade de Medicina da Universidade do Porto, Porto, Portugal.
authors.forename: Margarida
authors.initials: M
authors.lastname: Damasceno
authors.affiliation: Centro Hospitalar S João, Porto, Portugal.
authors.forename: Pedro
authors.initials: P
authors.lastname: Bastos
authors.affiliation: Centro Hospitalar S João, Porto, Portugal Departamento de Patologia e Oncologia Médica da Faculdade de Medicina da Universidade do Porto, Porto, Portugal Instituto de Patologia e Imunologia Molecular da Universidade do Porto (IPATIMUP), Porto, Portugal.
authors.forename: Manuel
authors.initials: M
authors.lastname: Sobrinho-Simões
mesh_terms: D015703:Antigens, CD / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism; D005260:Female; D006801:Humans; D007633:Keratins / Q000378:metabolism; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology*; D018242:Neuroectodermal Tumors, Primitive / Q000378:metabolism / Q000473:pathology*; D014746:Vimentin / Q000378:metabolism; D055815:Young Adult
chemical_list: D015703:Antigens, CD; D014408:Biomarkers, Tumor; D014746:Vimentin; D007633:Keratins
keywords: EWSR1; Ewing’s sarcoma/PNET; FLI1; lung cancer; neuroendocrine carcinoma; small round cell tumor