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  <Article>
    <Journal>
      <PublisherName>journal-jmsr</PublisherName>
      <JournalTitle>Journal of Medical and Surgical Research</JournalTitle>
      <PISSN>I</PISSN>
      <EISSN>S</EISSN>
      <Volume-Issue>Special Issue "Pathology"</Volume-Issue>
      <PartNumber/>
      <IssueTopic>Multidisciplinary</IssueTopic>
      <IssueLanguage>English</IssueLanguage>
      <Season>March, 2023</Season>
      <SpecialIssue>N</SpecialIssue>
      <SupplementaryIssue>N</SupplementaryIssue>
      <IssueOA>Y</IssueOA>
      <PubDate>
        <Year>-0001</Year>
        <Month>11</Month>
        <Day>30</Day>
      </PubDate>
      <ArticleType>JMSR Pathology</ArticleType>
      <ArticleTitle>TDT positive in blastic dermal infiltrate: think of blastic plasmacytoid dendritic cell neoplasm.</ArticleTitle>
      <SubTitle/>
      <ArticleLanguage>English</ArticleLanguage>
      <ArticleOA>Y</ArticleOA>
      <FirstPage>1152</FirstPage>
      <LastPage>1152</LastPage>
      <AuthorList>
        <Author>
          <FirstName>Sara</FirstName>
          <LastName>Chaabi</LastName>
          <AuthorLanguage>English</AuthorLanguage>
          <Affiliation/>
          <CorrespondingAuthor>N</CorrespondingAuthor>
          <ORCID/>
          <FirstName>Asmaa El</FirstName>
          <LastName>Kebir</LastName>
          <AuthorLanguage>English</AuthorLanguage>
          <Affiliation/>
          <CorrespondingAuthor>Y</CorrespondingAuthor>
          <ORCID/>
          <FirstName>Farida</FirstName>
          <LastName>Marnissi</LastName>
          <AuthorLanguage>English</AuthorLanguage>
          <Affiliation/>
          <CorrespondingAuthor>Y</CorrespondingAuthor>
          <ORCID/>
          <FirstName>Meriem</FirstName>
          <LastName>Regragui</LastName>
          <AuthorLanguage>English</AuthorLanguage>
          <Affiliation/>
          <CorrespondingAuthor>Y</CorrespondingAuthor>
          <ORCID/>
          <FirstName>Asmae</FirstName>
          <LastName>Mazti</LastName>
          <AuthorLanguage>English</AuthorLanguage>
          <Affiliation/>
          <CorrespondingAuthor>Y</CorrespondingAuthor>
          <ORCID/>
          <FirstName>Samira</FirstName>
          <LastName>Benayad</LastName>
          <AuthorLanguage>English</AuthorLanguage>
          <Affiliation/>
          <CorrespondingAuthor>Y</CorrespondingAuthor>
          <ORCID/>
          <FirstName>Nisrine Bennani -</FirstName>
          <LastName>Guebessi</LastName>
          <AuthorLanguage>English</AuthorLanguage>
          <Affiliation/>
          <CorrespondingAuthor>Y</CorrespondingAuthor>
          <ORCID/>
          <FirstName>Mehdi</FirstName>
          <LastName>Karkouri</LastName>
          <AuthorLanguage>English</AuthorLanguage>
          <Affiliation/>
          <CorrespondingAuthor>Y</CorrespondingAuthor>
          <ORCID/>
        </Author>
      </AuthorList>
      <DOI/>
      <Abstract>Background: Terminal deoxynucleotidyl transferase (TdT) is a DNA polymerase expressed in lymphoblastic lymphomas/leukemias but also in other undifferentiated tumors. An expression of Tdt in a blastic dermal infiltrate may constitute a diagnostic pitfall.&#13;
&#13;
Methods:  We present here a case diagnosed in our institution illustrating this diagnostic difficulty.&#13;
&#13;
Results : We report the case of an 81-year-old man, with no particular medical history, who had consulted for a purplish nodular dorsal mass accompanied by several diffuse infiltrated papular lesions that had evolved over several months.&#13;
&#13;
The biopsy showed a diffuse tumor infiltrate in the dermis, made of medium-sized cells with reduced cytoplasm and dense chromatin and separated from the epidermis by a grenz zone (Figure 1).&#13;
&#13;
The initial immunohistochemical study showed absence of CD3, CD8 and CD20 expression and expression of CD4, CD56 and TDT (Figure 2). Other lymphoid markers were requested to rule out lymphoma/lymphoblastic leukemia (PAX5, CD79a, CD5) as well as myeloid markers to rule out myelomonocytic leukemia (MPO, CD34, CD68, CD15), cytotoxic markers to rule out NK lymphoma (granzyme B and TIA1) and epithelial and neuroendocrine markers to rule out Merkel carcinoma. These markers were all negative, pointing to a blastic plasmacytoid dendritic cell neoplasm.&#13;
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Figure 1: HEx20 Figure 2: Tdt&#13;
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Conclusion: Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy with usually poor outcomes and high risk of progression to acute leukemia. Histological diagnosis is challenging and immunohistochemical analysis is mandatory. This entity represents a diagnostic challenge for pathologists given its rarity and possible TdT expression.</Abstract>
      <AbstractLanguage>English</AbstractLanguage>
      <Keywords>Terminal deoxynucleotidyl transferase, blastic dermal infiltrate</Keywords>
      <URLs>
        <Abstract>https://journal-jmsr.net/ubijournal-v1copy/journals/abstract.php?article_id=14388&amp;title=TDT positive in blastic dermal infiltrate: think of blastic plasmacytoid dendritic cell neoplasm.</Abstract>
      </URLs>
      <References>
        <ReferencesarticleTitle>References</ReferencesarticleTitle>
        <ReferencesfirstPage>16</ReferencesfirstPage>
        <ReferenceslastPage>19</ReferenceslastPage>
        <References>WHO Classification of skin Tumors, 4th Edition.&#13;
	Janine Wechsler et al ; Pathologie cutanand;eacute;e tumorale 2 and;eacute;dition, Sauramps Mand;eacute;dical.&#13;
	Jay L Patel et al. An unusual case of cutaneous blastic plasmacytoid dendritic cell neoplasm with concomitant B-cell lymphoproliferative disorder. The American Journal of Dermatopathology, 01 May 2011, 33(3):e31-6. DOI: 10.1097/dad.0b013e3181de9ce0&#13;
	Ming Sheng Lim, Karla Lemmert, and Anoop Enjeti. Blastic plasmacytoid dendritic cell neoplasm (BPDCN): a rare entity.BMJ Case Rep. 2016. doi: 10.1136/bcr-2015-214093</References>
      </References>
    </Journal>
  </Article>
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