Small bowel neoplasms

Dr nawin kumar

General Considerations

• Small bowel neoplasms are exceedingly rare – 80% of the total length – 5% of all GIT neoplasms – 1% - 2% of all malignant tumors of the GIT

• factors – rapid transit of luminal contents; – high turnover rate epithelial cells– alkalinity of small intestinal contents; – the high level of IgA in the intestinal wall– low bacterial count.

• equally distributed between men and women• age - old• geographic distribution- – highest cancer rates found among the Maori of

New Zealand and ethnic Hawaiians. – low in India, Romania

• most benign neoplasms are asymptomatic • found as an incidental finding. • Benign

– Leiomyomas and adenomas are the most frequent – more common in the distal small bowel– per unit area, duodenal tumors are most frequent.

• most common malignant neoplasm. – adenocarcinoma – carcinoid tumor

• site– Adenocarcinomas - proximal small bowel, – other malignant lesions - in the distal intestine

• risk – Crohn's disease – familial adenomatous polyposis – hereditary nonpolyposis colorectal cancer (HNPCC)– Peutz-Jeghers syndrome, – gluten-sensitive enteropathy (i.e., celiac sprue), – biliary diversion (e.g., previous cholecystectomy).

• Controversial factors – – smoking, – heavy alcohol consumption – red meat – salt-cured foods.

Diagnosis• Plain films – obstruction• Angiography is - tumors of vascular origin. • CT –

– extraluminal tumors such as (GISTs) – staging of malignant cancers

• Ultrasonography not proved to be effective • Barium follow through• CT enteroclysis• Flexible -duodenal lesions• colonoscope - terminal ileum • Push enteroscopy • radiotelemetry capsules (e.g., capsule endoscopy) • surgical exploration

Benign Neoplasms

• most common – benign GISTs- most common that produce

symptoms– adenomas- most common in autopsy– lipomas.

Clinical Manifestations

• Most patients asymptomatic • often nonspecific – dyspepsia, – anorexia, – malaise, – dull abdominal pain (often intermittent and

colicky).

Treatment

• risk for subsequent complications – obstruction – intussusceptions– Hemorrhage - usually occult; hematochezia or

hematemesis may occur– For final diagnosis - microscopic evaluation.

• polypectomy• Segmental resection and primary anastomosis • very small lesions- enterotomy. • entire small bowel searched - multiple.• pancreaticoduodenectomy

GISTs

• arise from the interstitial cell of Cajal, • intestinal pacemaker cell of mesodermal

descent. • incidence is equal in men and in women, • age - fifth decade of life

• intramurally - obstruction. • extramural growth- – achieving considerable size – outgrowing their blood supply – • ischaemic pain,• bleeding

• Grossly, – firm, gray-white – whorled appearance on cut surface;

• microscopic examination – well-differentiated smooth muscle cells. – spindle (70%) and epithelioid (30%) cells, – Most (>90%) GISTs express CD117, – c-kit proto-oncogene transmembrane protein – receptor for the stem cell growth factor, – 70% to 80% express CD34, the human progenitor cell antigen; – Sometime actin and desmin

Adenomas

• 15% of all benign small bowel tumors • Most common as asymptomatic• three primary types: – true adenomas, – villous adenomas – Brunner gland adenomas.

• Site– 20%- duodenum, – 30% - jejunum, – 50% - ileum.

• Villous adenomas – rare – most commonly - duodenum, – may be with FAP– propensity for malignant degeneration

• Brunner gland adenomas – – produce symptoms mimicking those of peptic

ulcer disease.

Lipomas

• Usually- single intramural lesions located in the submucosa.

• intusception

Hamartomas of the small bowel

• as part of the Peutz-Jeghers syndrome, • an inherited syndrome of mucocutaneous

melanotic pigmentation and gastrointestinal polyps.

• The pattern of inheritance is simple mendelian dominant with a high degree of penetrance

• classic pigmented lesions – small, 1- to 2-mm, – brown or black spots – location• circumoral region of the face, buccal mucosa, • forearms, palms, soles, digits, • perianal area. • entire jejunum and ileum

– may rectal and colonic lesions, gastric lesions.

• symptom – most common- colicky abdominal pain-

intermittent intussusception. – Hemorrhage – • Frank- autoamputation of the polyps• anemia.

• Extracolonic cancers are common- small intestine

• treatment –– directed to presentation– limited resection. – widespread nature of intestinal involvement, cure

is not possible

Hemangiomas • developmental malformations • submucosal proliferation of blood vessels. • Jejunum - most commonly affected but can involve any GIT• Rare• multiple in 60% of patients. • may occur as part

– Osler-Weber-Rendu disease. – Turner's syndrome

• Angiography and 99mTc–red blood cell scanning are the most useful diagnostic studies.

• intraoperative transillumination and palpation • Segmental resection

Malignant

• Carcinoid tumors • may arise in organs derived from the foregut,

midgut, and hindgut. • upto 80% of carcinoids are asymptomatic and

found incidentally • more than 90% in three sites: – the appendix (45%), – the ileum (28%), and – the rectum (16%)

AIR

• The malignant potential (ability to metastasize) is related to

• location, – Only 3% of appendiceal carcinoids metastasize, – but 35% of ileal carcinoids gets metastasis

• size, – <1 cm in diameter- 2% metastasis. In contrast, – 1 to 2 cm in diameter 50% metastasis – > 2 cm in diameter 90% metastasis

• depth of invasion, • growth pattern

• Grossly – small, firm submucosal nodules – multicentric in 20% to 30% – usually yellow on cut surface

• grow very slowly, • after invasion of the serosa- • intense desmoplastic reaction producing mesenteric fibrosis,

intestinal kinking, and intermittent obstruction. Small bowel carcinoids are of patients.

• frequent coexistence of a second primary malignant synchronous adenocarcinoma

• associated with MEN 1 in about 10% of cases.

• Clinical Manifestations– Local symptom- similar to other small bowel

tumors– carcinoid syndrome

• Malignant Carcinoid Syndrome• relatively rare disease < 10% of patients • humoral factors

– serotonin, – 5-hydroxytryptophan (a precursor of serotonin synthesis), – histamine, – dopamine, – kallikrein, – substance P, – prostaglandin, – neuropeptide K

• requirement– massive hepatic replacement by metastatic disease. – bypass the liver, specifically ovarian and retroperitoneal carcinoids,

• includes – vasomotor-

• cutaneous flushing• asthma

– cardiac,• pulmonary stenosis • tricuspid insufficiency • tricuspid stenosis

– gastrointestinal manifestations. • diarrhea (76%); • hepatomegaly

• Cutaneous flushing - four varieties: • diffuse erythematous,

– short lived – normally affects the face, neck, and upper chest;

• violaceous, – similar to diffuse erythematous flush – attacks may be longer – patients may develop a permanent cyanotic flush with watery eyes and

injected conjunctivae; • prolonged flushes,

– last up to 2 to 3 days – involve the entire body – profuse lacrimation, hypotension, and facial edema;

• bright-red patchy flushing, – which is typically seen with gastric carcinoids.

• diarrhea – episodic (usually occurring after meals), – watery, and often explosive

• Diagnosis• various humoral factors

– urinary levels of 5-HIAA measured over 24 hours • serotonin -liver and lung -inactive 5-hydroxyindoleacetic

– plasma concentrations of chromogranin A– Plasma serotonin, substance P, neurotensin, neurokinin A, and

neuropeptide K • Provocative tests using pentagastrin, calcium, or epinephrine may be

used to reproduce the symptoms of carcinoid tumors. • Barium radiographic studies –• multiple filling defects - kinking and fibrosis of the bowel • Angiography • high-resolution ultrasonography • somatostatin receptor scintigraphy using 111In-labeled pentetreotide.

Treatment

• based on – tumor size and site – presence or absence of metastatic disease

• <1 cm + no metastasis- a segmental intestinal resection

• > 1 cm, with multiple tumors + metastasis, -wide excision of bowel and mesentery is required.

• Lesions of the terminal ileum - right hemicolectomy. • duodenal - pancreaticoduodenectomy.

• metastatic disease- surgical debulking, • hepatic metastases- – wedge resection or formal hepatic lobectomy. – hepatic artery ligation or percutaneous

embolization

• Medical therapy -relief of symptoms caused by the excess production of humoral factors.

• analogues of somatostatin, such as octreotide • Interferon-α • Serotonin receptor antagonists –– Methysergide - retroperitoneal fibrosis. – Ketanserin and cyproheptadine

• Cytotoxic chemotherapy -limited success. – streptozotocin and 5-fluorouracil or cyclophosphamide

• Prognosis• Carcinoid tumors have the best prognosis of

all small bowel tumors, – Resection of a carcinoid tumor localized - 100%

survival rate. – Five-year survival rates are about 65% among

patients with regional disease and – 25% to 35% among those with distant metastasis

• carcinoid crisis during anaesthesia– hypotension,– bronchospasm, – flushing, – tachycardia to arrhythmias.

• The treatment - IV octreotide, antihistamine, hydrocortisone