GENERAL CONSIDERATIONS


Biologic Behaviour


General Considerations

•uncommon and accounts for 4%-9% of all feline cancers

•intestinal tumors (small and large) account for 68%-94% of all non-oral GI tumors

•small intestinal tumors are more common


Lymphosarcoma

•intestinal LSA is most common intestinal tumor in cats

•mean age 10-12 years (range, 1-18 years)

•breed predisposition: none

•role of FeLV and FIV uncertain as majority of cats with alimentary LSA are FeLV negative using serology and immunoflourescence assay, but many are positive using polymerase chain reaction

•replication defective, latent or low level or intermittent shedding are not detectable using traditional detection methods and may be involved in the etiopathogenesis of feline alimentary LSA

•proportion of T and B cell LSA varies with some reporting predominance of B cell immunophenotype, T cell immunophenotype, and equal distribution

•feline alimentary LSA is usually either:

•stage II: 32%, single resectable site ± mesenteric lymph node involvement

•stage III: 43%, single non-resectable site or extranodal secondary site


Adenocarcinoma

•intestinal ADC accounts for 20%-35% of all feline GI tumors

•mean age 11 years (range, 2-17 years)

•breed predisposition: Siamese

•intestinal ADC has no association with FeLV or FIV

•sites: small intestine and particularly jejunum or ileum

•histologic subtypes: tubular, undifferentiated, and mucinous

•tubular ADC may have a better survival rate than undifferentiated and mucinous ADC

•majority of feline intestinal ADC are advanced with 72% metastatic rate at diagnosis

•metastatic sites: peritoneum and regional lymph node are common, but others include liver, bone, and lungs


Duodenal Adenomatous Polyp

•mean age 12 years (range, 6-18 years)

•sex predilection: 83% male castrated


Globule Leukocyte Tumor

•characterized by large mononuclear cells with prominent azurophilic granules (= large, homogenous, peroxidase-positive granules of progranulocytes and early myelocytes that stain blue due to acid mucopolysaccharide content)

•diffuse metastasis at diagnosis is common


Mast Cell Tumor

•intestinal MCT is the 3rd most common feline GI tumor (after LSA and ADC)

•mean age 13 years

•histology: less differentiated with less prominent cytoplasmic granules

•more commonly involves small intestine with equal distribution between duodenum, jejunum, and ileum

•< 15% colonic involvement

•peritoneal effusion is relatively common but peripheral mastocytosis and eosinophilia is rare

•intestinal MCT is not associated with mucosal ulceration

•metastasis is common and sites include mesenteric lymph nodes and liver ± spleen, lung, and bone marrow


Other Intestinal Tumors

•leiomyoma and leiomyosarcoma are rare

•intestinal HSA has been reported in 4 cats, including 1 involving the small intestine

•carcinoids are rare


Clinical Signs

•anorexia, weight loss, and intermittent vomiting

•acute and chronic vomiting with hematemesis in cats with duodenal adenomatous polyps


Diagnosis


Physical Examination

•palpable abdominal mass and cachexia are common

•other findings include dehydration and abdominal pain


Laboratory Tests

•mild to moderate anemia common with intestinal LSA (43%) and ADC

•leukocytosis and neutrophilia ± lymphopenia

•paraneoplastic leukocytosis may be caused by production by either G-CSF or GM-CSF

•50% cats with intestinal tumors (mostly ADC) have hyperglycemia and 85% have elevated ALP

•other biochemistry abnormalities include mild hypokalemia, azotemia, and hypoproteinemia

•hypercalcemia reported in 1 cat with intestinal LSA

•moderate to marked anemia, azotemia, and elevated liver enzymes reported in cats with duodenal polyps


Abdominal Radiography

•abdominal mass frequently identified with feline intestinal LSA

•abdominal mass, bowel obstruction ± ascites identified in 21%-50% of cats with intestinal ADC


Contrast Radiography

•non-lymphoid intestinal mass and duodenal polyps are identified in 75% and 83% of cats, respectively

•survey radiographs may be sufficient to proceed with exploratory surgery without contrast studies

•contrast radiographs: mural lesions include luminal filling defect, intestinal wall thickening, mucosal ulceration, abnormal positioning of intestinal loops, and constricting annular lesions



From: Slatter DH (ed): Textbook of Small Animal Surgery (3rd ed).



Ultrasonography

•transmural thickening, loss of normal intestinal layering, localized masses, mesenteric lymphadenopathy, and peritoneal effusion are common findings with intestinal LSA ± hepatomegaly

•circumferential transmural thickening with loss of normal intestinal layering has been reported in 5 cats with intestinal ADC


Endoscopy

•endoscopy has been used successfully to identify duodenal polyps


Exploratory Celiotomy

•definitive diagnosis with exploratory celiotomy and biopsy

•feline ADC has gross appearance of annular scar-like constriction with variable degree of post-stenotic dilatation

•duodenal polyps are palpable and usually within 1 cm of the pylorus

•leiomyomas and sarcomas are usually large solitary masses growing through the intestinal serosa


Treatment


Surgery

•debilitation and hypoproteinemia may complicate treatment

•exploratory celiotomy with resection and end-to-end anastomosis with 4-8 cm margins and serosal patching of anastomosis

•mesenteric and regional lymph nodes should be assessed ± aspirated


Chemotherapy

•multiagent protocols recommended for LSA as either adjuvant therapy or sole treatment for diffuse disease

•chemotherapy is also recommended for cats with intestinal plasmacytoma and MCT

•no effective chemotherapy for ADC

•multiagent chemotherapy (L-asparaginase, prednisone, cyclophosphamide and vincristine) used in a cat with unresectable and diffuse globule leukocyte tumor with PR


Prognosis


Lymphosarcoma

•MST 201-280 days with a variety of different chemotherapy protocols

•60%-87% overall response rate with median response duration 120 days

•MST 11 months for cats with epitheliotropic intestinal LSA

•survival times were dependent on response to chemotherapy:

•survival times in cats refractory to chemotherapy were < 3.5 months

•survival times in cats responsive to chemotherapy were > 11 months


Adenocarcinoma

•50% local tumor recurrence rate in long-term survivors

•MST 5-15 months for surgery alone surgery

•survival time may be influenced by metastatic disease and histologic subtype

•mean survival time in cats with lymph node metastasis is 12 months v 15 months overall

•furthermore, 2 cats with omental carcinomatosis lived 4.5 months and 28 months after surgery

•mean survival time in cats with tubular ADC is 11 months v 4 months undifferentiated and mucinous ADC


Mast Cell Tumor

•poor prognosis as most cats die or euthanased soon after diagnosis

•solitary intestinal MCT without metastasis may have prolonged survival following end-to-end anastomosis


Duodenal Polyp

•surgical resection and end-to-end anastomosis can be curative

 

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