Colorectal Tumors, Uncommon

Carcinoids

• • 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

Lymphomas

• • 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

Sarcoma

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

  • Most common histologic subtype is leiomyosarcoma

  • Most significant prognostic indicator is tumor grade

Epidemiology

• • 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

Symptoms and Signs

• • Abdominal pain

  • Abdominal distention

  • Obstipation, constipation

  • Change in bowel habits

  • Weight loss

  • Hematochezia

  • Abdominal mass

• • Adenocarcinoma

  • Stricture: Inflammatory, radiation-induced

  • Appendicitis

  • Diverticular disease

Rule Out

• • Neoplasm

• • History and physical exam

  • Colonoscopy with biopsy

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

  • For lymphoma: Bone marrow biopsy

When to Admit

• • Bleeding

  • Obstruction

  • Perforation/peritonitis

Lymphoma

• • 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

Sarcoma

• • 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

Carcinoid

• • 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)

Surgery