Gastrointestinal stromal tumours

Gastrointestinal stromal tumours

Q. 1

Which of the following markers is specific for gastro-intestinal stomal tumor (GIST) –

 A

CD 117

 B

CD 34

 C

CD 23

 D

S-100

Q. 1

Which of the following markers is specific for gastro-intestinal stomal tumor (GIST) –

 A

CD 117

 B

CD 34

 C

CD 23

 D

S-100

Ans. A

Explanation:

Ans. is ‘a’ i.e., CD 117

lmmunohistochemistry

o Following markers are present in GISTs:

i)        CD 117 (c kit)                     —>95%

ii)      CD 34                                 —> 70%

iii)    Smooth muscle actin                  5%

  • CD 117 (c kit) is considered the most specific marker

o CD 117 (c kit) immunoreactivity is the best defining feature of GISTs distinguishing them from true smooth muscle tumors (leiomyoma) and tumors arising from neural crest.

o Although CD 117 (c kit) is considered the most specific marker for GIST, it is not pathognomonic of GIST as other tumors may also express CD 117. These tumors include mast cell tumor, germ cell tumors (seminomas), leukemias, malignant melanoma, angiolipomas, and some sarcomas.


Q. 2

The gene involved in GIST –

 A

C-KIT

 B

BRAC-1

 C

p53

 D

BRAC-2

Q. 2

The gene involved in GIST –

 A

C-KIT

 B

BRAC-1

 C

p53

 D

BRAC-2

Ans. A

Explanation:

Ans. is ‘a’ i.e., C-KIT

Pathogenesis of GISTs

o Approximately 75% to 80% of all GISTs have oncogenic, gain-of-function mutations of gene encoding the tyrosine kinase c-KIT

o Approximately 8% of GISTs have mutations that activate a related tyrosine kinase, platelet derived growth factor receptor a (PDGFRA).

o Consitutively active c-KIT or PDGFRA receptor tyrosine kinases activate RAS and P13K/AKT pathways and thereby promote tumor cell proliferation.


Q. 3

Not true about GIST –

 A

Stomach is the most common site

 B

High propensity of malignant change

 C

Associated with c-KIT mutation

 D

Histology shows spindle shaped cells

Q. 3

Not true about GIST –

 A

Stomach is the most common site

 B

High propensity of malignant change

 C

Associated with c-KIT mutation

 D

Histology shows spindle shaped cells

Ans. B

Explanation:

Ans. is ‘b’ i.e., High proportion of malignant change

The prognosis depends on tumor size, mitotic index & location.

o Recurrence or metastasis common for mitotic active tumors & more than 10cm but not for others.

Quiz In Between


Q. 4

Which of the following agents is recommended for treatment of Gastrointestinal Stromal Tumors (GIST) –

 A

Sorafenib

 B

Imatinib

 C

Gefitinib

 D

Erlotinib

Q. 4

Which of the following agents is recommended for treatment of Gastrointestinal Stromal Tumors (GIST) –

 A

Sorafenib

 B

Imatinib

 C

Gefitinib

 D

Erlotinib

Ans. B

Explanation:

Ans. is ‘b’ i.e., Imatinib

Tyrosine kinase inhibitors imatinib and sunitinib are approved for the treatment of Gastrointestinal Stromal Tumors (GIST)


Q. 5

A 50 yr. old male presents with obstructive symptoms. Biopsy of stomach reveals Gastrointestinal stromal tumor (GIST). Most appropriate marker for GIST is:

 A

CD 34

 B

CD 117

 C

CD 30

 D

CD 10T2 No Mo Anal Cancer

Q. 5

A 50 yr. old male presents with obstructive symptoms. Biopsy of stomach reveals Gastrointestinal stromal tumor (GIST). Most appropriate marker for GIST is:

 A

CD 34

 B

CD 117

 C

CD 30

 D

CD 10T2 No Mo Anal Cancer

Ans. B

Explanation:

Ans is ‘b’ i.e. CD 117 

  • Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumor of the GI tract and are most frequently located in the stomach (60%-70%).
  • In 1983, Mazur and Clark coined the term GIST to indicate a distinctive subgroup of GI mesenchymal tumor, which could be classified neither as neurogenic nor as smooth muscle derived tumor. Historically, they were presumed to have smooth muscle origin and classified as leiomyomas, leiomyoblastomas, and leiomyosarcoma.
  • They are considered to originated from the interstitial cell of Cajal, an intestinal pacemaker cells.
  • Almost all GISTs (and almost no smooth muscle tumors) express c-KIT (CD117) or the related PDGFRA, as well as CD34. Kit is a transmembrane tyrosine kinase receptor, the ligand for which is stem cell factor. The Kit protein is detected by immunohistochemistry and can reliably distinguish GISTs from true smooth muscle neoplasms. (Note that almost all smooth muscle tumors (and almost no GISTs) express actin and desmin.
  • KIT is used not only for diagnosis but also for targeted therapy of GISTs. Imatinib, a tyrosine kinase inhibitor, is widely used in the treatment of advanced and metastatic GISTs and has been recently employed in the neo adjuvant and adjuvant set-up with encouraging results.
  • Surgical resection of the localized GIST is the mainstay therapy, as a resection of tumor renders only a chance of cure. The primary goal of surgery is complete resection of the disease with negative margins.
  • GISTs are resistant to both chemotherapy and radiotherapy. Therefore until the advent of Imatinib, there was no effective treatment available for the unresectable or metastatic GISTs. The development of Imatinib mesylate has revolutionized the management of this disease.
  • Imatinib mesylate (formerly referred to as STI 571, GleevecTM) is a 2-phenylpyrimidine derivative that blocks binding of ATP to ABL tyrosine kinases including c-Kit, c-ABL, bcr-ABL, and the platelet-derived growth factor receptor (PDGFRA). Imatinib was developed as a PDGFR inhibitor. The efficacy of Imatinib mesylate as a tyrosine kinase inhibitor was first assessed in chronic myeloid leukemia (CML), which is associated with mutation in bcr­ABL tyrosine kinase similar to the role of KIT in GIST.
  • Prognosis in patients with GIST tumors depends mostly on tumor size and mitotic count, and metastasis.
  • GISTs metastasize through hematogenous route. Usual sites are infra-abdominal, either to the liver, omentum, or peritoneal cavity. (Ref: Devita’s Oncology 8/e).

Q. 6

Marker specific for Gastrointestinal Stromal Tumor (GIST):        

September 2012

 A

CD117

 B

CD34

 C

CD23

 D

S-100

Q. 6

Marker specific for Gastrointestinal Stromal Tumor (GIST):        

September 2012

 A

CD117

 B

CD34

 C

CD23

 D

S-100

Ans. A

Explanation:

Ans. A i.e. CD117

Gastrointestinal stromal tumor (GIST)

  • It is one of the most common mesenchymal tumorsof the gastrointestinal tract (1-3% of all gastrointestinal malignancies).
  • They are typically defined as tumors whose behavior is driven by mutations in the Kit gene or PDGFRA gene, and may or may not stain positively for Kit.
  • When GIST is suspected — as opposed to other causes for similar tumors — the pathologist can use immunohistochemistry (specific antibodies that stain the molecule CD117 [also known as c-kit] — see below).
  • 95% of all GISTs are CD117-positive (other possible markers include CD34, DOG-1, desmin, and vimentin).
  • Other cells that show CD117 positivity are mast cells

Quiz In Between


Q. 7

What is false about GIST ‑

 A

Associated with NF 1

 B

Most common site is stomach

 C

Associated with CD 117

 D

Least common mesenchymal neoplasm of gas­trointestinal tract

Q. 7

What is false about GIST ‑

 A

Associated with NF 1

 B

Most common site is stomach

 C

Associated with CD 117

 D

Least common mesenchymal neoplasm of gas­trointestinal tract

Ans. D

Explanation:

Ans. is ‘d’ i.e., Least common mesenchymal neoplasm of gastrointestinal tract

Gastrointestinal stromal tumors (GISTs)

GISTs are the most common mesenchymal neoplasm of gastrointestinal tumor.

GIST represents a distinct group of gastrointestinal tumors that originate from the interstial cells of cajal which control gastrointestinal peristalsis.

GISTs can occur anywhere in the gastroinstestinal tract; the most common site being the stomach followed by small intestine.


Q. 8

Which of the following is not true about GIST ‑

 A

Stomach is the most common site

 B

High propensity of malignant change

 C

Associated with c-KIT mutation

 D

Histology shows spindle shaped cells

Q. 8

Which of the following is not true about GIST ‑

 A

Stomach is the most common site

 B

High propensity of malignant change

 C

Associated with c-KIT mutation

 D

Histology shows spindle shaped cells

Ans. B

Explanation:

Ans. is ‘b’ i.e., High propensity of malignant change

Pathogenesis of GISTs

  • Approximately 75% to 80% of all GISTs have oncogenic, gain-of-function mutations of gene encoding the tyrosine kinase c-KIT
  • Approximately 8% of GISTs have mutations that activate a related tyrosine kinase, platelet derived growth factor receptor a (PDGFRA).
  • Consitutively active c-KIT or PDGFRA receptor tyrosine kinases activate RAS and P131f/AKT pathways and thereby promote tumor cell proliferation.
  • The prognosis depends on tumor size, mitotic index & location.
  • Recurrence or metastasis common for mitotic active tumors & more than 10cm but not for others.

Q. 9

Which of the following is not true about Gastrointesti­nal Stromal Tumor (GIST)?

 A

Originates from interstitial cells of Cajal

 B

Most common mesenchymal tumour of gastrointesti­nal tract

 C

Prognosis depends on size

 D

ALK gene mutation is seen in most of the cases

Q. 9

Which of the following is not true about Gastrointesti­nal Stromal Tumor (GIST)?

 A

Originates from interstitial cells of Cajal

 B

Most common mesenchymal tumour of gastrointesti­nal tract

 C

Prognosis depends on size

 D

ALK gene mutation is seen in most of the cases

Ans. D

Explanation:

Ans. d. ALK gene mutation is seen in most of the cases

Quiz In Between



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