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Carcinoids

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  • • Uncommon in large bowel; most occur in the rectum

    • Lesions < 2 cm in diameter usually are asymptomatic, behave benignly, and can be managed by local excision

    • Larger tumors arising in the colon (mainly the right side) or rectum cause local symptoms, often metastasize, and require standard cancer resection

    • Carcinoid syndrome appears in fewer than 5% of patients with metastatic carcinoid of the large bowel

    • Derived from cells that are capable of synthesizing a wide variety of hormones

    • 60% of rectal carcinoids present as asymptomatic submucosal nodules measuring < 2 cm in diameter

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Lymphomas

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  • • Rare; account for < 0.5% of all colorectal malignancies

    • The documentation of widespread dissemination of lymphoma in most cases underscores the concept that lymphoma of the GI tract is a systemic disease in which tumor cells are present in other organ sites

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Sarcoma

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  • • Extremely rare: account for < 0.1% of all large bowel malignancies

    • Most common histologic subtype is leiomyosarcoma

    • Most significant prognostic indicator is tumor grade

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Epidemiology

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  • Carcinoids of the colon are uncommon (2% of GI carcinoids) and most of them occur in the rectum (15% of GI carcinoids)

    Lymphomas are the most common noncarcinomatous malignant tumors of the large bowel; primary non-Hodgkin colonic lymphoma account for 10% of GI lymphomas

    Sarcomas represent < 1% of colonic tumors, with peak incidence in sixth decade of life

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Symptoms and Signs

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  • • Abdominal pain

    • Abdominal distention

    • Obstipation, constipation

    • Change in bowel habits

    • Weight loss

    • Hematochezia

    • Abdominal mass

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  • • Adenocarcinoma

    • Stricture: Inflammatory, radiation-induced

    • Appendicitis

    • Diverticular disease

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Rule Out

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  • • Neoplasm

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  • • History and physical exam

    • Colonoscopy with biopsy

    Staging studies: Chest film, abdominal CT scan, liver function tests

    For lymphoma: Bone marrow biopsy

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When to Admit

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  • • Bleeding

    • Obstruction

    • Perforation/peritonitis

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Lymphoma

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  • • Because this disease is highly responsive to chemotherapy and radiation, surgery is not always the primary mode of therapy

    • Usually, for localized, low-grade colorectal lymphomas, radiation is considered first-line therapy

    • Intermediate- and high-grade lymphomas, chemotherapy combined with radiation therapy should be the primary treatment

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Sarcoma

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  • • If the tumors are clinically localized at initial presentation, a radical en bloc excision should be performed to obtain a margin of uninvolved normal tissue; nodal dissection indicated if gross nodal involvement

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Carcinoid

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  • • Surgery mainstay of therapy, degree of resection depends on size (lesions > 2 cm may require formal resection; < 2 cm may be amenable to local excision)

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Surgery

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Indications

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  • Rectal carcinoid: Transanal local excision suffices for definitive therapy because small tumors rarely metastasize

    Lymphoma: Surgery has been primarily for diagnostic and staging purposes and for the management of treatment-related complications (ie, perforation or bleeding).

    Sarcoma: If tumors are clinically localized at initial presentation, a radical en bloc excision should be performed to obtain a margin of ...

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