Cancer: Other GI Tumors Flashcards
Where are leiomyomas typically found in the esophagus?
The distal 1/3.
What is the most common mesenchymal tumor of the esophagus?
Leiomyoma.
How do leiomyomas typically present?
Dysphagia.
Where in GI tract are you unlikely to find leiomyomas?
The stomach and small bowel. They are usually in the esophagus and colon.
What markers are expressed by leiomyomas?
Smooth muscle actin and desmin.
What is the most common mesenchymal tumor of the GI tract?
A gastrointestinal stromal tumor (GIST).
What markers are typically expressed by GISTs?
c-Kit, a tyrosine kinase.
What is the cell of origin for GISTs?
The interstitial cells of Cajal, which are pacemakers for GI motility.
In which layer of the GI tract can the interstitial cells of Cajal typically be found?
In the muscularis propia, near the myenteric plexuses. (They can similarly be found in the muscularis mucosa near submucosal plexuses.)
Why is it thought the GISTs derive from interstitial cells of Cajal?
They both express c-Kit.
What characteristics do GISTs that are c-Kit negative usually have?
(1) epithelioid morphology
(2) PDGFRA mutations
How are GISTs treated?
(1) surgical resection
(2) imatinib, a tyrosine kinase inhibitor (especially effective for c-Kit positives)
(3) sunitinib malate, for the imatinib-resistant
Where in the GI tract are GISTs most common?
The stomach, followed by the small bowel.
What is an important initial indicator of malignancy for GISTs?
Location. 20% of GISTs in the stomach are malignant, compared to half in the small bowel and a majority in the colon and esophagus (though they are rare in these latter locations).
Size and mitotic count are also important.
What genetic disorders are associated with GISTs?
(1) neurofibromatosis type 1
(2) Carney’s triad
What is Carney’s triad?
A generic disorder in young females characterized by:
(1) GISTs
(2) pulmonary chondromas
(3) paragangliomas
What are the 3 general categories of neuroendocrine tumors?
(1) well-differentiated NET
(2) poorly-differentiated neuroendocrine carcinoma, small cell type
(3) poorly-differentiated neuroendocrine carcinoma, large cell type
Where in the wall of the GI tract can neuroendocrine cells typically be found?
They are concentrated at the base of crypts and glands, thus NETs typically develop at the junction of the mucosa and submucosa.
How do NETs appear, grossly?
Yellow-tinged sessile nodules, usually with an intact or slightly eroded surface.
What is a characteristic cytological feature of NETs?
Salt and pepper chromatin.
What are markers of NETs on immunohistochemistry?
(1) synaptophysin
(2) chromogranin
(3) CD56
Which GI tract NETs are more aggressive: functional or non-functional?
Functional.
What causes carcinoid syndrome?
A serotonin-secreting NET.
What is the clinical presentation of carcinoid syndrome?
(1) flushing
(2) diarrhea and abdominal cramps
(3) right-sided heart disease (fibrosis of tricuspid valve)
Why is carcinoid syndrome arising from a GI NET usually a sign of malignancy?
Serotonin released from the GI tract is typically inactivated by first-pass metabolism by the liver. Thus if the patient presents with symptoms, the tumor has likely metastasized.
What genetic disorder is associated with gastrinomas?
MEN 1.
Why are gastrinomas more often symptomatic?
Gastrin is metabolized by the kidney, thus it is subject to first pass metabolism in the liver.
What are the gross changes in ZES?
(1) thickened rugal folds in the stomach
(2) peptic ulcers
What is the most common site for extranodal lymphomas?
The GI tract, with stomach, small bowel and colon in decreasing order.
What are predisposing factors for GI lymphomas?
(1) infection
(2) celiac disease
(3) IBD
(4) immunodeficiency
What path do B cells take in their maturation once leaving the bone marrow?
In the lymph node:
(1) mantle zone
(2) germinal center
(3) marginal zone or paracortex
What is the cell of origin in MALT lymphoma?
Marginal zone B cells.
What is the cell of origin in follicular lymphoma?
Germinal center B cells.
Where are MALT lymphomas most common?
The stomach.
What condition are MALT lymphomas most associated with?
H. pylori infection.
What genetic anomaly is most associated with MALT lymphoma?
A t(11:18) translocation, particularly in cases that do to respond to treatment of H. pylori infection.
What are complications of more advanced MALT lymphomas?
(1) transformation to diffuse large B cell lymphoma
(2) metastasis
How are MALT lymphomas treated?
(1) treat H. pylori infection
(2) surgery, radiation, chemo
What is a concerning histological finding in MALT lymphoma?
Lymphoepithelial lesion.
Where is the most common location for follicular lymphoma in the GI tract?
The small bowel.
J: This refers to a presentation of follicular lymphoma in which there are multiple polyps.
What is lymphomatous polyposis?
What is in the ddx for lymphomatous polyposis?
(1) reactive lymphoid hyperplasia (HIV)
(2) mantle zone lymphoma
(3) follicular lymphoma
What cytogenetic anomaly is associated to follicular lymphoma?
A t(14:18) translocation resulting in a rearrangement of BCL2.
In what location in the GI tract is mantle zone lymphoma most common?
The colon.
What cytogenetic anomaly is most associated with mantle zone lymphoma?
A t(11:14) translocation resulting in an over expression of cyclin D1.
J: This cancer is characterized by a starry sky pattern with tingible body macrophages on histology.
What is Burkitt lymphoma?
What is the most common cytogenetic anomaly in Burkitt lymphoma?
A t(8:14) translocation involving c-myc.
What types of Burkitt lymphoma typically present in the abdomen?
(1) non-endemic
(2) immunodeficiency-associated
What lymphoma has a high association with celiac disease?
Enteropathy-type T cell lymphoma.
How can you differentiate celiac disease from enteropathy-type T cell lymphoma?
(1) cellular atypia
(2) aberrant T cell antigen expression
(3) T cell clonality
