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      <JournalTitle>Frontiers in Medical Case Reports</JournalTitle>
      <Volume-Issue>Volume 1; Issue 2</Volume-Issue>
      <Season>(Mar-Apr, 2020)</Season>
      <ArticleType>Medical Case Reports</ArticleType>
      <ArticleTitle>Osseous Metaplasia in a Rectal Inflammatory Polyp in an Adolescent Patient: A Case Report and Review of the Literature</ArticleTitle>
      <Abstract>Osseous metaplasia/heterotopic bone formation is a well-known phenomenon encountered in various neoplastic and non-neoplastic conditions. Osseous metaplasia in colorectal polyps is extremely rare. We report a case of osseous metaplasia in a rectal inflammatory polyp in a 17-year-old man with a longstanding history of painless rectal bleeding. The patient was referred to our facility for evaluation of a four-month history of painless rectal bleeding, as well as rectal prolapse and episodes of fecal urgency. A total colonoscopy revealed an approximately 1.0 cm tan-red sessile and pedunculated polyp in the rectum. No other abnormalities were identified in the colon. The polyp was removed via snare polypectomy. On gross examination, the polyp measured 1.2 x 1.1 x 0.8 cm and was quadrisected and submitted entirely for histologic examination. Sections of the polyp showed fragments of denuded polypoid colonic mucosa with inflammatory granulation tissue formation and overlying purulent debris. The inflammatory granulation tissue was composed of abundant dilated small blood vessels, a marked mixed acute and chronic inflammatory infiltrate, and active fibroblast proliferation. At the junction of the intact colonic mucosa and the adjacent inflammatory granulation tissue, multiple foci of woven bone formation without bone marrow were identified. Osseous metaplasia most likely occurs by osteoblasts differentiating from fibroblasts secondary to inflammation, tissue damage, or substances such as bone morphogenetic proteins released from neoplastic cells. Osseous metaplasia could also be caused by dystrophic calcification in necrotic tissue. To our knowledge, this is the eighth reported case of osseous metaplasia in a rectal inflammatory polyp.</Abstract>
      <Keywords>Osseous metaplasia,Inflammatory polyp,Rectum,Adolescent</Keywords>
        <Abstract>https://jmedicalcasereports.org/ubijournal-v1copy/journals/abstract.php?article_id=7314&amp;title=Osseous Metaplasia in a Rectal Inflammatory Polyp in an Adolescent Patient: A Case Report and Review of the Literature</Abstract>
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