other neoplasms of stomach
TRANSCRIPT
OTHER NEOPLASMSOTHER NEOPLASMSOF STOMACHOF STOMACH
By Dr.R.Vinoth Prabu
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Prof Dr.S.R.Dhamotharan MS IV Surgical unitAssistants:Dr Shanthi Nirmala MSDr Celine Foustina Mary MSDr Arulraj Kumar MS
Constitutes 10%
• Lymphoma 3-4%
• Mesenchymal tumors– GIST 1-2%– leiomyosarcoma 1% others 1%
• Endocrine tumors 1%– Carcinoid - commonest
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• Stomach – MC site of primary GI Lymphoma(95% NHL)
• Sixth to seventh decades
• Most common B cell type(MALT) Next DLBCL
• H.Pylori
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55-65%
20-35%
7-20%
What is MALT?
– Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT)
– Heterogeneous, predominantly small B-lymphocytes 5Lymphoepithelial lesions
Dawson’s criteria
• No palpable superficial lymphadenopathy
• No mediastinal involvement on CXR
• Normal Total & Diff. Count
• At surgery– disease limited to dominant bowel lesion and adjacent
nodes– No liver or spleen involvement
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• Distinct group of mesenchymal tumors recognized after
1990 with IHC
• Adults
• M>F
• Small asymptomatic GISTs are found at autopsy in more than 50 % of individuals over the age of 50
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GISTs are identified by
either c-kit immunoreactivity (detection of the CD117 antigen) or the presence of activating mutations in kit or PDGFRA
cell of origin – interstitial cells of cajal– c.kit proto oncogene is responsible for development of
tumor
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Cellular Morphology
• Three relatively distinctive types
Spindle cell type – 70 percent Epithelioid type – 20 percent, more commonly c-kit negative
and found in omentum and mesentery Mixed type – 10 percent.
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Histopathology
• Differential Diagnosis • H&E stain: Melanoma, leiomyoma/sarcoma,
peripheral nerve sheath tumor, desmoid • Histology difficult
• Immunophenotyping crucial 95 % are positive for C-kit (CD117) 60-70 % positive for CD34 • Negative for alpha-smooth muscle actin
(SMA) (leiomyoma) • Negative for S100 protein (Schwannoma) • Negative for Desmin (desmoids)
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Metastasis
GISTs behave differently than other soft tissue sarcomas:
• GISTs frequently metastasize to the liver and rarely to regional lymph nodes
• GISTs virtually never metastasize to lungs whereas this is the most common site of metastasis for leiomyosarcomas
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Clinical Manifestations
• Mesenchymal tumors of the GI tract are often asymptomatic and discovered incidentally during endoscopic or barium studies.
• Overt GI bleeding — 40 percent • Abdominal mass — 40 percent • Abdominal pain — 20 percent
• The vast majority of GIST metastases at presentation are intra-abdominal, either with metastases to the liver, omentum, or peritoneal cavity .
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Imatinib (Gleevec) a Tyrosine Kinase Inhibitor
• Imatinib mesylate is a protein-tyrosine kinase inhibitor that inhibits the Bcr-Abl tyrosine kinase.
• Thyrosine kinase inhibtor effective in metastatic and unresectable disease.
• Shows > 50% regression.
• Duration of therapy not yet known. 22
TUMOR ARISING FROM LESSER CURVATURE STOMACHTUMOR ARISING FROM LESSER CURVATURE STOMACHAND GROWING INTO LESSER OMENTUMAND GROWING INTO LESSER OMENTUM
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• Composed of argyrophlic ECL cells
• 8% of all GI Carcinoids
• Pernicious anemia and atropic gastritis
• 5% will produce carcinoid syndromes
• Carcinoid tumors of stomach produce atypical symptoms or asymptomatic
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