GIT 6 Flashcards
(10 cards)
What are the morphological features of a neuroendocrine (carcinoid) tumor?
Grossly: appear as small, yellowish, brown nodules. Histologically: nests, trabeculae, glands or sheets of uniform polyhedral cells, with scant pink granular cytoplasm and round-to-oval nuclei with salt and pepper chromatin (stippled nuclei).
What is the most important prognostic factor for neuroendocrine (carcinoid) tumors?
The most important prognostic factor is the location of the tumor.
What are the risk factors for colorectal adenocarcinoma?
Premalignant lesions: Adenomatous polyps, inflammatory bowel diseases. Genetic factors: Familial adenomatous polyposis (FAP) 100% risk, microsatellite instability pathway (defects in DNA mismatch repair gene). Environmental factors: High fat and high carbohydrate diets, low fibers in diets. Use of aspirin and other NSAIDs exerts a protective effect against colon cancer.
What are the gross features of colorectal adenocarcinoma in the proximal (right) colon?
Tumors of the proximal (right) colon appear as exophytic, polypoid masses in the ascending colon and cecum. They may ulcerate, causing occult bleeding and iron deficiency anemia. Obstruction is uncommon.
What are the histological features of colorectal adenocarcinoma?
Adenocarcinoma ranges from well differentiated to undifferentiated, frankly anaplastic tumors. The invasive component elicits a strong stromal desmoplastic response, responsible for their characteristic firm consistency. Many tumors produce mucin (Mucinous Adenocarcinoma), which worsens the prognosis. Sometimes signet ring carcinoma is present, as in gastric carcinoma.
What are the two most important prognostic factors for colorectal adenocarcinoma?
The two most important prognostic factors are the depth of invasion and the presence or absence of lymph node metastases.
What initiates acute appendicitis?
Acute appendicitis is initiated by progressive increases in intraluminal pressure that compromise venous outflow. Obstruction is the primary event, mostly by fecaliths.
What are the complications of acute appendicitis?
Complications include gangrene, perforation leading to peritonitis, and intra-abdominal abscess.
What is the most common tumor of the appendix?
The most common tumor of the appendix is the carcinoid tumor, which is most often discovered incidentally and is almost always benign.
What are the morphological types of Gastrointestinal Stromal Tumors (GIST)?
The morphological types of GIST are spindle (most common), epithelioid, and mixed.
