intestinaltumor

Small intestinal tumor,Despite comprising 75% of the length and 90% of the surface area of the GI tract, the small bowel harbors relatively few primary neoplasms and fewer than 2% of GI malignancies.,WHY THIS LOW INCIDENCE ?,2.Greater fluidity of chyme may dilute luminal irritants.,3.Alkaline pH may play a role,4. Low bacterial counts make them less capable of transforming potential procarcinogens to carcinogens,1. Rapid intestinal transit limits contact time to the mucosa.,5.Higher levels of benzyl peroxidase (thought to detoxify potential carcinogens) have been detected,6. Increased levels of immunoglobulin A,7.Widespread gut lymphoid tissue,SMALL INTESTINAL NEOPLASMS COULD BE :,BENIGN: GI stromal tumors (GIST) (45%) Adenomas (20-40%) Lipomas (16%) Hemangiomas (13%) Lymphangioma (5%) Neuroma (1%) S.intestinal polyps,MALIGNANT: Carcinoids (47%) Adenocarcinomas (25%) Lymphomas (16%) Sarcomas or GIST (1%) Metastasis (1%),SMALL INTESTINE TUMORS,BenignEpithelialTumors,MalignantEpithelialTumors,Lympho-proliferative disorders,MesenchymalTumors,BrunnerGlandLesions,BenignIntestinal polypi,T cell,B cell,GIST,Fattytumors,Neuraltumors,Paragangl.,Smooth Mstumors,Vasc.tumors,LipomaLiposarcoma,Gut autonoic tumor Schwannoma Neurofibroma Granular cell tumor,Leioyomayoma Leioyomayosarcoma,Haemangioma Angiosarcoma Lymphangioma Kaposi sarcoma,BenignMalignant,EnteropathyassociatedT-cell lymphoma,Diffuse large cell lymphoma.Small non cleaved cell lymphoma.MALT cell lymphoma.Mantle cell lymphoma.Immuonoproliferative small cell disease,Pr. ADCMetastasis.Carcinoid.,AdenomasHamartomas,SYMPTOMS,Small bowel tumors are mostly ASYMPTOMATIC, but in symptomatic cases there is lack of specific identifying symptom; no hallmark presentation has been described.,The interval from symptom onset to diagnosis ranges from less than a month to more than a year, with a mean duration of symptoms of 6 months., Abdominal pain: This is generally nonspecific, and epigastric in location. Pain is more commonly associated with larger lesions. Constipation Nausea Vomiting Early satiety Anorexia Diarrhea Palpable mass Anemia Melena,SI tumors may manifest primarily with complications of their growth., Bowel obstruction: the leading cause of intussusception in adults. Volvulus: from serosal ependymal lesions GI bleeding: occurs in up to 38% of lesions. Perforation, Usually unrevealing. larger tumors (6 cm), may manifest as a palpable abdominal mass. Tenderness on the mass may be elicited.,PHYSICAL EXAMINATION,DIAGNOSIS OF SMALL INTESTINAL NEOPLASMS,Routine laboratory testing do not reveal abnormalities in most patients.,CEA levels may be elevated in malignant tumors.,LABORATORY STUDIES,Liver function tests may reveal hyperbilirubinemia, which may be related to biliary obstruction from periampullary tumors. Elevated transaminase levels also may be found in the presence of liver metastases.,CBC count may show mild anemia related to chronic blood loss.,Large lesions may demonstrate signs of complete or partial small bowel obstruction on plain films (eg, dilated small bowel, air-fluid levels, volvulus).,Barium contrast studies may demonstrate the lesion in up to 29% of cases. The radiographic appearance includes irregular mucosal surfaces, barium-filled cavities (showing central lesion necrosis), and dumbbell-shaped lesions (indicating intraluminal and extraluminal growth) Enteroclysis,IMAGING,CT scan demonstrate up to 27% of SI tumors especially when larger than 2 cm.,IMAGING (cont.),Accurate size, evidence of ulceration and lesion necrosis are often detected.,IMAGING (cont.),On arteriograms tumors are identified by characteristic tumor blush . Additional clues include multiple feeding arteries, irregular draining veins, and venous pooling around the lesion.,Arteriography may assist in differentiating malignant from benign lesions: Benign tumors receive arterial supply from either the GD or SM arteries. Malignant lesions often demonstrate aberrant arterial inflow from renal arteries, lumbar arteries, or both.,Ultrasound images may demonstrate larger tumors (4 cm) giving a mass or target sign appearance. US can help differentiate if the mass is intraluminal, intramural, and extraluminal exophytic growth patterns.,IMAGING (cont.),Luminal small bowel tumors may cause intussusception giving rise to a mass with layered appearance by US.,IMAGING (cont.),IMAGING (cont.),Also, EUS is valuable in smaller tumors.,IMAGING (cont.),MRI is useful to determine the extent of the tumor in the abdomen although usually CT scans are adequate.,It is also useful in looking for recurrence or metastases.,IMAGING (cont.),PET has become one of the most useful tests for spotting GIST tumors. Radioactive glucose is used which is consumed much faster by the malignant tissues.,It may be a useful test for staging the cancer and for determining drug efficacy.,ENDOSCOPY,Upper endoscopy has been employed successfully for the detection of proximal lesions in 30% of cases.,It allows biopsy of intraluminal lesions. Polypectomy may be performed for small lesions.,Push enteroscopy may identify lesions in the distal duodenum and jejunum.,ENDOSCOPY (cont.),GISTs and lipomas cannot be removed via endoscopy because of their deep intramural location and the subsequent elevated risk of bowel perforation during removal attempted.,In addition, some authors caution against endoscopic biopsy because of increased risk of shedding cells, which could lead to nests of local tumor recurrence.,Colonoscopy with retrograde ileoscopy may be useful in identifying ileal tumors.,ENDOSCOPY (cont.),By capsule endoscopy both color video images and transit time values can be analyzed for regional mucosal abnormalities.,In cases where all these investigations are negative and the index of suspicion remains high, then a laparotomy is indicated and if no lesion is palpable, an intraoperative enteroscopy should be done.,ENDOSCOPY,BENIGN SMALL INTESTINAL NEOPLASMS,S.I.ADENOMAS,Three types of adenomas have been described: adenomatous polyps, Brunner gland adenomas, and villous adenomas.,Histologically, they appear as intraluminal extensions of the mucous membrane and submucosal architecture with multiple acini supported on a central fibrovascular core. Varying degrees of differentiation are encountered across and within tumors.,Adenoma in duodenum,Tubular adenoma,Villous adenomas larger than 4 cm are at particular risk for malignant transformation.,S.I. LIPOMA,Small bowel lipomas are benign submucosal tumors of mesenchymal origin.,Pathology includes collections of mature adipose tissue and fibrous tissue strands.,Collections of adipose tissue may be found near the ileocecal valve. These deposits may clinically mimic other lesions, both radiographically and endoscopically.,S.I. HEMANGIOMA,Hemangiomas of the small bowel are rare vascular tumors of 3 types: capillary, cavernous (most common), and mixed.,Hemangiomas may be solitary or multiple and may account for up to 13% of small bowel lesions.,Preoperative arteriography or intraoperative maneuvers, such as transillumination or ultrasound, may be employed to increase localization success.,GI bleeding is a frequent complication. The blood loss may be occult (resulting in chronic anemia) or acute.,S.I. NEUROMA,Also, all patients with MEN 2B have intestinal neuromas.,Neurofibromatosis type 1 (von Recklinghausen disease of nerve) affects the GIT in up to 25% of cases, and in such cases is characterized by multiple submucosal neurofibromas.,Patholoy shows spindle cells in loose fibromyxoid background, spindle cells may expand the lamina propria and separate the crypts,Spindle cells stains with S100, chromogranin, neuron specific enolase,S.I. POLYPS, Familial adenomatous polyposis Gardners syndrome. Lynchs syndrome. Turcots syndrome. Peutz-Jeghers syndrome. Juvenile polyposis.,MALIGNANT SMALL INTESTINAL NEOPLASMS,EPIDEMIOLOGY,Prevalence: prevalence is lower in less industrialized countries. In addition, lymphomas are predominant in less developed countries.,Race: higher prevalence rates for blacks than for whites,Sex: Males have higher prevalence compared with females, with a ratio of 1.4:1,Age: The prevalence tends to increase with age,RISK FACTORS,Familial adenomatous polyposis,Hereditary nonpolyposis colorectal cancer,Diet: animal fat, red meat and salt-cured or smoked foods,Tobacco and alcohol,Crohns disease,Celiac disease,S.I. ADENOCARCINOMA,Epidemiologically, small-bowel adenocarcinomas have a striking resemblance to large-bowel adenocarcinomas:,1. They share a similar geographic distribution.,2. They tend to co-occur in the same individuals, with an increased risk of SI adenocarcinoma in survivors of CRC and vice versa,3. SI adenocarcinoma arise from premalignant adenomas both sporadically and in the context of FAP.,4. K-ras mutation and p53 over-expression appear to be as common in SI adenocarcinoma as in CRC.,S.I. ADENOCARCINOMA (cont.),Despite these similarities, SI adenocarcinomas have differences from CRC:,1. Small-bowel adenocarcinomas tend to cluster away from the colon, toward the gastric end of the small intestine.,2. Mutation of the APC tumor suppressor gene, which is characteristic of colorectal carcinoma, does not commonly occur in small-bowel adenocarcinoma,3. The SMAD4/DPC4 gene, which is often mutated in pancreatic and colorectal carcinomas, also appears to be inactivated in small-bowel adenocarcinomas,S.I. ADENOCARCINOMA (cont.),Of patients with SI carcinoids, 40-50% experience the syndrome.,S.I. CARCINIOD,Patients with SI carcinoids frequently have symptoms for long periods ( 2-5 or more y) before diagnosis is made.,In this group of patients, early diagnosis can potentially lead to a cure by surgical resection of the primary tumor.,Obstruction in SI occurs due to: Desmoplastic reaction: Invasion of the mesentery with scarring and matting of loops. Mass effect.,S.I. CARCINIOD (CONT.),Carcinoid syndrome is rarely observed in association with appendiceal carcinoids, and does not occur with rectal carcinoids, even when the it is in an advanced stage and has metastasized.,SI is an uncommon site for metastasis. Primary tumors include: Melanoma, Carcinomas from bronchus, breast, thyroid, colon, pancreas, prostate, uterus, ovary and testicular malignancy.,S.I. METASTASIS,Metastatic deposits lie within the wall usually within the submucosa. US shows a focal mural mass which may or may not have a target sign.,Disorders that predispose patients to SI lymphoma include previous extraintestinal lymphoma, chronic lymphocytic leukemia, celiac disease, and immunologic dysfunction, including AIDS,Lymphoma represents approximately 20% of primary malignancies of the small intestine,S.I. LYMPHOMA,It is considered to be primary if the predominant lesion is in the intestine and the initial presenting symptoms are related to intestinal involvement.,The ileum is the mostly affected location (more lymphoid tissue),CT findings include mural infiltration of the wall with homogenous, asymmetric wall thickening (2 cm) and a nodular appearance of the mass.,Aneurysmal dilatation (seen by BMFT) is pathognomonic of small-bowel lymphoma and refers to a segmentally dilated lumen with associated wall thickening and without proximal bowel dilation,S.I. LYMPHOMA (cont.),In addition, CT often reveals mesenteric or retroperitoneal lymphadenopathy, a hallmark of this disease.,On CT, lymphoma is softer and longer than adenocarcinoma, and it has ill-defined, thickened walls with irregular or complete loss of the normal mucosal folds.,By US tumors appear as multiple well defined hypoechoic masses in GI wall.,S.I. LYMPHOMA (cont.),Extensive lymphomatous involvement of the stomach create the pathological “cochade” pattern.,Early stages present as localized thickening of mucosa, while global wall thickening, destruction of wall stratification, and visibility of draining LN can be observed in later stages.,TREATMENT OF SMALL INTESTINAL NEOPLASMS,Surgical excision of small bowel tumors remains the recommended therapy.,SURGERY,Both segmental resection and enterotomy/polypectomy have been used for lesion removal.,If the pathology cannot be established at the time of resection, full segmental resection with adequate margins is recommended.,No standard regimen demonstrates benefit in an adjuvant or metastatic setting for small-bowel adenocarcinoma.,CHEMOTHERAPY:,Because of the similarity to CRC, a regimen containing 5-FU with leucovorin may be used. Newer agents as irinotecan and oxaliplatin, may also be used with 5-FU.,GASTROINTESTINAL STROMAL TUMORS (GIST),GI STROMAL TUMORS,GI stromal tumors are the most common symptomatic small bowel lesions. They have been found in all areas of the small bowel, including within the Meckels diverticulum.,They are mesenchymal neoplasms derived from the interstitial cells of Cajal in the GI tract.,Pathology shows nests of spindle-shaped cells located between the muscularis propria and muscularis mucosa. These intramural lesions may form intraluminal masses, extraluminal masses, or transmural (dumbbell-shaped) lesions.,By US, GIST appear as well defined hypoechoic masses arising from the GI wall, their shape is variable ( often eccentrically oval), large tumors may be circular. Large GIST may contain cystic areas, have a pedicle and/or may be mobile and change position, which makes it difficult o define their site of origin. Small GIST can only be detected by hydrosonography or EUS.,While most GISTs are located in the stomach, 30% of GISTs are found in the small bowel. Small-bowel GISTs tend to be more aggressive and have a worse prognosis.,Previously, these tumors were classified as GI leiomyomas, leiomyosarcomas, leiomyoblastomas, or schwannomas as a result of their histologic findings and apparent origin in the muscularis propria layer of the intestinal wall.,With the advent of immunohistochemical staining techniques and ultrastructural evaluation, GISTs now are recognized as a distinct group of mesenchymal tumors.,Nearly all GISTs, unlike true sarcomas, express mutations in c-kit that cause constitutive tyrosine kinase activity and result in uncontrolled cell proliferation,1.Sporadic GISTs a. Mutations of c-kit receptor tyrosine kinase (KIT) gene b. Mutations of PDGFR-alpha gene coding for platelet-derived growth factor receptor Alpha 2. NF-associated GISTs a. NF germline mutations b. No KIT or PDGFRA mutations,Etiology,GI STROMAL TUMORS (GIST) (CONT.),GI STROMAL TUMORS (GIST) (CONT.),The exact definition of GISTs varies among authors. Some use the term to describe any GI submucosal mesenchymal tumor that is not myogenic (eg, leiomyosarcoma) or neurogenic (eg, schwannoma) in origin. Others are more restrictive and use the term when specifically referring to GI mesenchymal tumors that express the CD117 and/or CD34 antigen.,The CD34 protein is a hematopoietic progenitor cell antigen that occurs in a variety of mesenchymal tumors. CD117 also is known as the c-kit protein; it is a membrane receptor with a tyrosine kinase component. Mutations in the CD117 gene have been linked to mal