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GI Week 2 > Lecture 21: Other GI Tumors > Flashcards

Lecture 21: Other GI Tumors Flashcards

1
Q

What are the crypts of Lieberkuhn?

A

The crypts next to villi in small bowel

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2
Q

What is the mucosa?

A
  1. epithelium
  2. lamina propria (LP)
  3. muscularis mucosae (MM)
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3
Q

What layers of the GI tube are made of smooth muscle? Significance?

A

Muscularis mucosae
Muscularis Propria
This is where smooth muscle tumors are derived from (mesenchymal origin)

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4
Q

What are the two types of tumors in smooth muscle origin?

A
  1. Leiomyoma (benign) and most common

2. Leiomyosarcoma (malignant)

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5
Q

What is the most common mesenchymal tumor of the esophagus?

A

Leiomyomas
-typically lower 1/3 of esophagus
Presents with dysphagia
UNCOMMON in the stomach and small bowel

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6
Q

What are the histological features of Leiomyomas?

A
  1. Expresses smooth muscle markers:
    i. smooth muscle actin (SMA)
    ii. desmin
  2. Bland elongated spindle shaped cells, eosinophilic cytoplasm
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7
Q

What is the most common mesenchymal tumor of the esophagus?

A

Leiomyoma

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8
Q

The cells in a leiomyoma express what immunohistochemical markers?

A

C. Smooth muscle actin (SMA) and desmin

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9
Q

What are GISTs?

A

Gastrointestinal stromal tumor
The most common mesenchymal tumor of the ENTIRE GI tract but rare in esophagus and colon
Arise in small bowel and stomach

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10
Q

What are the histochemical markers of GIST?

A
  1. Most are positive for c-kit (CD117)
  2. driven by KIT or PDGRFA activating mutations
  3. thought to be derived from interstitial cells of Cajal (ICC)
    - pacemaker cells of the GI tract
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11
Q

c-kit? Significance?

A

Associated with GIST

Medications target tyrosine kinase c-kit like imatinib

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12
Q

What is the most common mesenchymal tumor in the ENTIRE GI tract? Just the esophagus?

A

GIST (gastrointestinal stromal tumor)

For esophagus, it is the leiomyoma

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13
Q

What are the most important features to predict the behavior of a GIST?

A
  1. location (stomach does better)
  2. size (smaller does better)
  3. mitotic count ( lower proliferation does better)
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14
Q

What are the histological features of GIST?

A

Ice cream cones

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15
Q

What are ice cream cones associated with histologically?

A

Gastrointestinal stromal tumor (GIST)

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16
Q

What are epithelioid cell GIST?

A

Only LOOKS like an epithelioid cell
c-kit
characterized by a PDGFRA mutation

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17
Q

What minority does not have c-kit mutation in GIST?

A

5%
Remaining will have PDGFRA mutation with epithelioid look
Also DOG1

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18
Q

Why should KIT-negative GISTs not, a priori, be denied imatinib therapy?

A

Because paradoxically, kit-negative GISTs can contain imatinib sensitive KIT or PDGFRA mutations!

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19
Q

What is the treatment for GIST?

A
  1. tyrosine kinase inhibitors such as imatinib (Glevac)
  2. Sunitinib malate (used for patients resistant to imatinib)
  3. surgical resection
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20
Q

What is the impact of different types of mutations in GIST?

A

Response is dictated by mutations!
Exon 11 = responds GREAT to therapy
Exon 9 = responds TERRIBLY to therapy

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21
Q

Where are GISTs most common?

A
  1. stomach

2. small intestine

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22
Q

What are the hereditary associations?

A
  1. Neurofibromatosis type 1
  2. Carney’s triad (young females)
    i. Gastric epithelioid GISTs
    ii. Pulmonary Chondroma (hamartomas)
    iii. Paragangliomas
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23
Q

What is Carney’s triad?

A
  1. gastric epithelioid GISTs
  2. Pulmonary chondroma (hamartomas)
  3. Paragangliomas
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24
Q

What are the neuroendocrine cells?

A
  1. specialized epithelial cells
  2. neuro relates to the production of peptides and amines (like neurons do)
  3. stored in neurosecretory granules
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25
Q

How do you tell what a neuroendocrine cell is?

A

The stained red part is pointed TOWARDS the lumen

The red stained part for Paneth cells is pointed away from the lumen

26
Q

What are the tumors that arise from NE cells?

A
  1. well-differentiated neuro endocrine tumor (NET)
    Aka carcinoid and aka islet cell tumors
  2. Poorly-differentiated neuroendocrine carcinoma (small cell type)
    -small cell carcinomas
    -aggressive with high N/C ratios
  3. Poorly-differentiated neuroendocrine carcinoma, large cell type
    -uncommon, very aggressive
    -more cytoplasm seen in small cell carcinomas
27
Q

What are the key characteristics of well-differentiated neuroendocrine tumors (NET)?

A
  1. aka carcinoid
  2. called tumors because behavior hard to predict
  3. can be functional (ie clinically secrete a hormone) or nonfunctional
28
Q

What are the histological features of neuroendocrine cells?

A

Are epithelium but they are derived at the mucosa-submucosa junction so looks mucosy
Salt and peppered chromatin
Concentrated at the base of crypts and glands

29
Q

What are the NE markers?

A
  1. Synaptophysin (know for Step)
  2. Chromagranin (know for Step)
  3. CD56
30
Q

What does salt n pepper nuclear chromatin

Suggest about the cancer?

A

Suggiestive of a neuroendocrine tumor

Possibly a carcinoid tumor

31
Q

What are the two NETumors that are focused on in the lecture?

A
  1. NET that secretes serotonin (carcinoid syndrome)

2. NET that secretes gastrin (ZES)

32
Q

What is the effect of serotonin on the gut?

A
  1. increases GI motility

2. increases GI blood flow

33
Q

What are the manifestations of carcinoid syndrome?

A

Due to increased serotonin or 5-HT

  1. Flushing of the skin
  2. Diarrhea and abdominal cramps
  3. Right sided heart disease due to fibrosis of the tricuspid valve
  4. increased urinary excretion of 5-HIAA (5-hydroxyindoleaceetic acid), a degradation product of serotonin
34
Q

Why does carcinoid syndrome usually imply metastatic disease if NET is from luminal GI tract?

A

When the primary tumor is in the GI tract, the serotonin is inactivated by the liver (first pass metabolism)
Therefore, manifestations of carcinoid syndrome do not occur until they are metastases (usually to the liver
Applies only to the GI tract

35
Q

What are carcinoid tumors?

A

WELL-DIFFERENTIATED neuroendocrine tumors

36
Q

What are small cell carcinomas?

A

POORLY differentiated neuroendocrine tumors

37
Q

A patient with flushing, diarrhea and right side heart disease has a tumor in the terminal ileum that has salt n pepper nuclear chromatin on H&E stained sections. This tumor is likely to stain with what immunohistochemical stains?

A
  1. Synaptophysin and Chromagranin
  2. 5100
  3. Actin and desmin (Leiomyoma)
  4. Ckit and CD34 (GIST)
38
Q

The tumor resected from a neuroendocrine tumor patient presenting with symptoms is likely?

A

B. Malignant

39
Q

What are the key characteristics of a gastrinoma (Gastrin producing NET)?

A
  1. gastrin is metabolized in the kidney so first pass metabolism doesn’t work
  2. associated with ZES
  3. associated with MEN-1
40
Q

What are the characteristics of lymphomas in the GI tract?

A
  1. The GI tract is the most common site for extranodal lymphomas
  2. Stomach most often involved, followed by small intestine and colon
  3. predisposing factors including
    i. infection (H PYLORI)
    ii. celiac
    iii. IBS
    iv. Immunodeficiency disorders
41
Q

What are the types of lymphomas of GI tract?

A
  1. Low grade B-cell lymphomas
    i. Marginal Zone lymphoma (aka MALT lymphoma)
    ii. follicular lymphoma
    iii. Mantle Cell lymphoma (more aggressive)
  2. High grade B-cell lymphomas
    i. Diffuse Large B-cell lymphoma
    ii. Burkitt Lymphoma
  3. T-cell lymphomas
    i. Enteropathy-type T-cell lymphoma
42
Q

What are the key characteristics of marginal zone B-cell lymphoma?

A
  1. most common associated with H pylori gastritis!
  2. most common site = stomach
  3. 75% respond to H pylori eradication
43
Q

What is the key translocations of marginal zone B-cell lymphoma?

A

The mutation is a t(11:18) API2-MALT1
The translocation between 11 and 18 at API2-MALT1
Resistant to H pylori treatment!!

44
Q

What are the key characteristics of follicular lymphoma?

A

T(14:18) BCL-2 rearrangement (no apoptosis) so there are a shitload of mature cells in the follicular zone

45
Q

What are the common sites for the GI lymphomas?

A

MALT = stomach (associated with H pylori!!)
Follicular lymphoma = small bowel
Mantle Zone lymphoma = colon

46
Q

What is the 3 differential diagnoses for lymphamatous polyposis?

A
  1. Reactive lymphoid hyperplasia
  2. Mantle zone lymphoma
  3. Follicular lymphoma
47
Q

What is lymphamatous polyposis?

A

Polyps that form from nonHodkin lymphoma (below)

48
Q

What is the cytogenetics

Of Follicular lymphoma?

A

T(14:18) and BCL-2 rearrangement

49
Q

What does BCL-2 do?

A

Prevents cells from undergoing

Apoptosis

50
Q

What is the key characteritics of

Mantle cell lymphoma?

A

A DDx of lymphomatous polyposis

Very AGGRESSIVE

51
Q

What are the cytogenetics of Mantle Cell lymphoma?

A

T(11:14)

Translocation causes overexpression of cyclin D1

52
Q

What is cyclin D1?

A

A promoter of progression of cell cycle

53
Q

What are the key characteritics of Diffuse large b-cell lymphoma

A

The most common lymphoma of the GI tract
LARGE lymphocytes
Relatively abundant cytoplasm

54
Q

What are the characteristics of Burkitt Lymphoma?

A

Derived from GERMINAL center B-cells
Starry sky appearance
Tingible bodies macrophages are gobbling up apoptotic debris within sea of medium sized lymphocytes

55
Q

What is the translocation associated with Burkitt?

A

T(8:14)

56
Q

What are the key characteristics of enteropathy type T cell lymphoma?

A

Remember that it is associated with celiac disease!
Often associated with or preceded by so-called REFRACTORY SPRUE
-not responsive to gluten free diet
-typically involves jejunum or ileum
-very aggressive
-you will see variable mixed size of lymphocytes

57
Q

What lymphoma is celiac disease associated with?

A

Enteropathy type T cell lymphoma

58
Q

What is t(8:14)?

A

Burkitt lymphoma (c-myc)

59
Q

What is t(11:18)?

A

MALT (marginal zone)

60
Q

What is t(11:14)?

A

Mantle Cell

61
Q

What is t(14:18)?

A

Follicular lymphoma

GI Week 2 (15 decks)

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