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GI > Other GI Tumors > Flashcards

Other GI Tumors Flashcards

1
Q

What are the 3 categories of “other” (non-epithelial) tumors we’re talking about in the GI?

A

Mesenchymal -e.g. smooth muscle.
Neuroendocrine
Hematologic (e.g. lymphoma)

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2
Q

Are leiomyosarcomas common in the GI tract?

A

Very rare.

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3
Q

Where are leiomyomas most commonly found in the GI tract? Where are they uncommon?

A

Most common: Esophagus, also colon.

Uncommon in the stomach and small intestine.

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4
Q

Immunohistochemical stains for leiomyoma? (2 things)

A

Smooth muscle actin (SMA)

Desmin

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5
Q

What’s the most common mesenchymal tumor of the GI tract?

A

GIST - gastrointestinal stromal tumor

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6
Q

From what cell do GISTs probably arise? Where are these cells?

A

Interstitial cells of Cajal (ICCs) - pacemaker cells.

These cells are associated both this submucous plexus and myenteric plexus.

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7
Q

For what stain are most GISTs positive?

What’s different about the ones that don’t stain for it?

A

c-kit - about 95%

The rest are more likely to be epithelioid in morphology, and be driven by PDGFRA mutations.

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8
Q

What mutations are thought to drive GISTs?

A

KIT or PDGRFA

- both are gain of function mutations

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9
Q

Histological buzzwords for GIST?

A

Spindle cell, “ice cream cones.”

Or epithelioid.

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10
Q

What’s a new stain (other than c-kit) for GISTs?

A

DOG1

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11
Q

Treatments for GIST?

A

Surgery.

Tyrosine kinase inhibitors (esp Imatinib - Gleevec)

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12
Q

What is GIST response to imatinib based upon?

A

Type of mutation in the the tumor.

Best with exon 11/Kit, worst with exon 9.

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13
Q

Where are GISTs most common in the GI tract?

A

Most common in the stomach, then small intestine.
Rare in colon and esophagus.
(the opposite distribution from leiomyomas)

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14
Q

3 variables in GIST prognosis?

A

Location
Size
Mitotic count

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15
Q

2 hereditary associations with GIST?

A

NF1

Carney’s triad

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16
Q

What’s Carney’s triad?

A

Young females with …
Gastric epithelioid GISTs
Pulmonary chondroma (hamartomas)
Paragangliomas

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17
Q

What does the “neuro” in neuroendocrine (NE) cells refer to?

A

Production of peptides and amines stored in neurosecretory granules.

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18
Q

How can you distinguish NE cells from Paneth cells?

A

NE granules point basolaterally.

Paneth granules point toward the lumen.

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19
Q

3 categories of NE tumors (NETs)?

Which is most common in the GI tract?

A

Well-differentiated NE tumor - most common in GI tract.
Poorly-differentiated NE carcinoma, small cell type.
Poorly-differentiated NE carcinoma, large cell type.
(the latter 2 are very aggressive, but less common)

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20
Q

Why do NE tumors often have intact epithelium over them?

A

They arise from the epithelial - submucosal junction and push up the epithelium above them.

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21
Q

Buzzword for the histological appearance of NET nuclei?

A

Salt and pepper (or salt-n-pepa) nuclei.

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22
Q

3 NE markers you should know about?

A

Synaptophysin
Chromogranin
CD56

23
Q

What does it mean for an NET to be functional? How does this relate to aggressiveness?

A

Functional = producing hormones.

In GI tract, functional usually means more aggressive.

24
Q

Which cells in the GI tract make 5-HT, and what does it do?

A 
Enterochromaffin cells (ECs)
5-HT increases GI motility and blood flow.
25
Q

What do you call the syndrome where there’s a GI tumor making 5-HT?

A

Carcinoid syndrome.

26
Q

Symptoms of carcinoid syndrome?

A

Flushing, diarrhea, right sided heart disease (due to fibrosis of tricuspid valve).
- can detect excess 5-HIAA (5-HT breakdown product) in urine.

27
Q

Why does carcinoid syndrome imply metastatic disease? (probably an important concept)

A

When it’s a primary tumor, the 5-HT is mostly broken down in the liver by first pass metabolism.
When the tumor metastasizes, its hormones can disseminate systemically, causing symptoms.

28
Q

Why is it important to diagnose gastrinoma? (3 reasons)

A

They’re aggressive.
Could be associated with MEN1.
ZES -> ulcers.

29
Q

How can you have gastrinoma symptoms without metastasis?

A

Gastrin is metabolized renally, so it isn’t affected by first-pass metabolism.

30
Q

What are some pre-disposing factors for GI lymphoma?

A

Infection (esp. H. pylori)
Celiac
IBD
several immunodeficiencies

31
Q

What are 3 common low grade B-cell lymphomas?

A

Marginal Zone Lymphoma (aka MALT lymphoma).
Follicular lymphoma.
Mantle cell lymphoma. - most aggressive.

32
Q

2 high grade B-cell lymphomas?

A

Diffuse large B-cell lymphoma.

Burkitt Lymphoma.

33
Q

3 parts of a normal B cell follicle, from inside out? What low-grade B cell lymphomas come from each?

A 
Germinal center - Follicular lymphoma.
Mantle zone (naive B cells) - Mantle zone lymphoma.
Marginal zone (mature B cells) - Marginal zone (aka MALT) lymphoma.
34
Q

Most common association with Marginal Zone aka. MALT lymphoma? Treatment?

A

H. pylori

Treatment = H. pylori eradication.

35
Q

If MALT lymphoma doesn’t respond to H. pylori eradication, what transformation does it likely have? Effect?

A

t(11:18): API2-MALT1

Causes transformation to Diffuse Large B-cell Lymphoma -> spread.

36
Q

Where do you see an expanded marginal zone and “lymphoepithelial lesions”?

A

Marginal zone aka. MALT lymphoma.

37
Q

Where do most follicular lymphomas occur? How do they appear grossly?

A

Mass-like lesions in the small intestine.

38
Q

What are 3 things on the DDx for lymphomatous polyposis?

A

Reactive lymphoid hyperplasia (usu. in HIV).
Mantle zone lymphoma.
Follicular lymphoma.

39
Q

How does a follicular lymphoma look different from a reactive follicle?

A

It’s crowded and “looks clonal” - whatever that means.

40
Q

Most common gene rearrangement in follicular lymphoma?

A

t(14:18) BCL-2

Recall: BLC-2 is anti-apoptotic. GC B-cells should be primed to die, and thus shouldn’t express BCL-2.

41
Q

Mantle cell lymphoma: indolent or aggressive?

A

aggressive

42
Q

What translocation drives mantle cell lymphoma? What does this cause?

A

t(11,14): Form IgH-Cyclin D1 (BCL-1) fusion that drives Cyclin D1 overexpression.

43
Q

Take home part about Diffuse Large B-Cell Lymphoma (DLBCL)?

A

Had large lymphocytes… and it’s agressive.

High mitotic rate.

44
Q

What’s the histological buzzword for Burkitt Lymphoma?

A

“Starry Sky” pattern due to “tingible body macrophages” amid rapidly dividing lymphocytes.

45
Q

Translocation that drives Burkitt Lymphoma? (in 80% of cases)

A

t(8:14) - c-myc to IgH

46
Q

Of the endemic, sporadic, and immunodeficiency-associated presentations of Burkitt Lymphoma, which usually present in the abdomen?

A

Sporadic and immunodeficiency-associated Burkitt’s usually present with abdominal lymphoma.
(Endemic usu. presents in Jaw/facial area.)

47
Q

What is Enteropathy-type T Cell Lymphoma associated with?

A

Celiac disease that is refractory to gluten-free diet.

48
Q

Histological buzzword for enteropathy-type T cell lymphoma?

How do you know it’s not celiac?

A

Mixed inflammatory background - eosinophils, plasma cells, and histiocytes.
(Atypia, immunohistochemistry, loss of CD8s, T cell monoclonality tell you it’s not celiac)

49
Q

What is t(14:18) - aberrant BCL2 expression associated with?

A

Follicular Lymphoma

50
Q

What is t(11:14) - Cyclin D1 overexpression associated with?

A

Mantle Cell Lymphoma.

51
Q

What is t(8,14) - c-myc overexpression associated with?

A

Burkitt Lymphoma

52
Q

What is t(11,18) associated with?

A

Marginal Zone aka MALT Lymphoma

53
Q

Which lymphoma is caused by H. pylori / can be resistant to treatment of H. pylori?

A

MALT Lymphoma.

GI (45 decks)

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