Small Bowel and Appendix
Even though the Small Intestine is the longest part of the GI tract, it has less than 5% of all the neoplasms of the GI tract!!
Benign tumors of the Small Intestine
Brunner’s Gland Adenoma
- can be both focal or diffuse
- usually found on the posterior wall of the duodenum at the junction between the 1st and 2nd part of the duodenum
Leiomyoma
- Leiomyoma = smooth muscle
- Should be called leiomyoma of the small intestine because the most frequent site of leiomyoma is the uterus.
- Ulceration of mucosa can be present
Lipoma
- Lipoma = benign, soft, rubbery, encapsulated tumor of adipose tissue, usually composed of mature fat cells.
- In GI tract, usu. Seen at distal ileum at ileocecal valve
- Has a characteristic x-ray appearance
Adenomas
- Adenoma = benign epithelial tumor in which the cells form recognizable glandular structures
- In GI tract, usually found in the jejunum. Can be found in the duodenum around the ampulla of Vater
- VERY HIGH INCIDENCE OF MALIGNANT TRANSFORMATION!!
CLINICAL PRESENTATION OF BENIGN S.I. TUMORS
- abdominal pain in recurrent episodes
- intestinal obstruction
- GI bleeding
- Intussusception = prolapse of one part of the intestine into the lumen of an immediately adjacent part.
Malignant Tumors of the Small Intestine
Adenocarcinoma
- 50 times more common in the colon than in the S.I.
- usu. Occurs in elderly patients
- 40-50% of all cases in the duodenum particularly around the ampulla of VATER
- polypoid (resembling a polyp) and fungiating mass occurs in 20% of patients
Predisposing Conditions to Adenocarcinoma
- Crohn’s Disease (regional enteritis)
- Sprue – chronic form of malabsorption syndrome; tropical and non-tropical forms
- Gardner’s Syndrome (Hereditary polyps)
Malignant Lymphoma
- can be 1o or 2o
- 2o involvement from retroperitoneal lymph nodes seen in 10% of patients
- B cell type is usually MALT
- There is also a T cell type
Predisposing Conditions to Malignant Lymphoma
- celiac sprue – a malabsorption syndrome precipitated by ingestion of gluten-containing foods, with loss of villous structure of the proximal mucosa, bulky, frothy diarrhea, abdominal distension, flatulence, weight loss, and vitamin and electrolyte loss.
- Regional enteritis (Crohn’s disease)
- Organ transplantation
- AIDS
Carcinoid
- Most common GI malignant tumor
- Found anywhere along the GI tract
- LOW GRADE
- Originates from neuroendocrine cells (enterochromaffin cells)
- Can be functional or non-functional
- Serotonin, gastrin, ACTH, or somatostatin
- SIZE MATTERS
1) Tumors < 1 cm – rarely metastasize
2) Tumors between 1-2 cm – 50% metastasize
3) Tumors > 2 cm – 80% metastasiza
- PATHOLOGY
Ø Gross
1. submucosal yellow nodules
2. may be polypoid, intramural, and ulcerative
Ø MICRO
1. nest, cords, and rosettes of uniform small round cells
2. seldom do you see mitoses
- CARCINOID SYNDROME
Ø The syndrome develops from unregulation of the secretory products of the abdominal carcinoid tumor (Ex. Serotonin or kallikrein). The liver usually inactivates the secretory products from the tumor once they drain into the liver via the portal system.
Ø liver metastasis present in95%
Ø only 75% of those that mave metastases to the liver develop carcinoid syndrome
Ø You can find 5 HIAA in the urine
Ø CLINICAL FINDINGS
1) cutaneous flashes
2) diarrhea
3) bronchospasm
4) personality changes
5) subendocardial fibrosis
6) valvular deposits
Ø life span 3 years after onset of the carcinoid syndrome
Appendix
Acute Appendicitis
- adolescence and young adults (but can occur at any age)
- MOST FREQUENT SURGICAL EMERGENCY
- ETIOLOGY/PATHOGENESIS
Ø ulceration of the mucosa
Ø bacterial invasion of the wall
Ø obstruction of the lumen leads to circulatory changes
Ø Causes: fecalith (50%), lymphoid hyperplasia, worms, and tumors
Ø The secretions accumulate and cause luminal distension which leads to venous dilation through engorgement which leads to arterial compromise and mucosal ischemia
- PATHOLOGICAL ANATOMY
Ø GROSS
1. normal to slightly dilated
2. purulent exudate
3. thickened wall (mucosal ulceration)
4. pus and fecal material in lumen
Ø MICRO
1. Acute inflammation in one of the corners of the vermiform lumen
2. Spreading of inflammation occurs
- CLINICAL
Ø periumbilical pain
Ø anorexia, nausea, vomiting
Ø McBurney’s point – right lower quadrant, 1/3 the distance on an imaginary line from the Right Anterior Ilicac Spine to the umbilicus. If there is pain there in rebound, suggests appendicitis.
Ø Fever and leukocytosis
- DDx
Ø mesenteric lymphadenitis, PID, ectopic pregnancy, ovulatory pain, Meckel’s diverticulum, inflamatory bowel disease
- large number of false +s because of 2% of mortality assoc. with perforation.
- COMPLICATIONS
Ø perforation
Ø Pylephlebitis – spread of inflammation through the portal vein to the liver.
Tumors of the Appendix
Mucocele
- Not a diagnosis
- GROSS diagnosis for enlarged appendix with dilated lumen that contains mucus
- Mucocele- many different conditions
- Occlusion of lumen by tumor, endometriosis
Other
- hyperplastic mucosal changes
- adenomatous
- carcinoids
Tags: Adenocarcinoma, anorexia, Appendicitis, bronchospasm, Brunner's Gland Adenoma, Carcinoid Syndrome, epithelial tumor, Leiomyoma, leukocytosis, Lipoma, liver metastasis, lymphoid hyperplasia, Malignant Lymphoma, nausea, Pylephlebitis, subendocardial fibrosis, vomiting
