Gastrointestinal stromal tumour

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The gastrointestinal stromal tumour, abbreviated GIST, is an uncommon tumour of the gastrointestinal tract.

General

Epidemiology

  • Arise from Interstitial cells of Cajal.[1]
  • Classically splits the layers of the muscularis propria - as this is where the interstitial cells of Cajal are located.[2]

Factors predictive of malignant behaviour

Features suggesting a bad prognosis:[1]

  • Large size.
    • Often benign if small size.
  • High mitotic rate (for area 5mm^2).
  • Site - small intestine GISTs worse than stomach GISTs.

Small intestine bad prognosis:[1]

  • >5 mitoses/5 mm^2 or size >10 cm.

Stomach bad prognosis:[1]

  • >5 mitoses/5 mm^2 and size >5 cm.

Location

Most common locations in order:[1]

  • 60% in stomach.
  • 35% in small intestine.
  • 5% elsewhere.

Small intestinal GISTs have a worse prognosis than gastric ones.[1]

Definition

  • Mutation in the Kit gene or PDGFRA (Platelet-derived growth factor receptor, alpha polypeptide) gene.[1]

Microscopic

Features:

  • Classically, spindle cell morphology; however, may be epithelioid (round).
  • +/-Cytoplasmic inclusions.[3]

IHC

  • CD34 +ve in 70%.[1]
  • CD117 +ve in 95%.[1]
    • Mast cells are the internal positive control.
  • Desmin +ve in 5%.[1]

ICH Work-up panel

  • S-100 (neural tumours, rarely +ve in GISTs[1]).
  • CD34, CD117 (GIST).
  • Desmin (muscle tumours).

DDx

  • Leiomyosarcoma.
  • Leiomyoma.
  • Neural tumours.
    • Neurofibroma.
    • Schwannoma (GFAP +ve).
      • GFAP uniformly neg. in GISTs.[1]

Special tests

  • Sequence Kit gene, PDGFRA gene.
    • Kit gene sequencing is being done more frequently as of late-- if a mutation is found it suggest the drug imatinib will be effective.

Treatment

See also

References

  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 Miettinen M, Lasota J (October 2006). "Gastrointestinal stromal tumors: review on morphology, molecular pathology, prognosis, and differential diagnosis". Arch. Pathol. Lab. Med. 130 (10): 1466–78. PMID 17090188. http://journals.allenpress.com/jrnlserv/?request=get-abstract&issn=0003-9985&volume=130&page=1466.
  2. Agaimy A, Wünsch PH (August 2006). "Gastrointestinal stromal tumours: a regular origin in the muscularis propria, but an extremely diverse gross presentation. A review of 200 cases to critically re-evaluate the concept of so-called extra-gastrointestinal stromal tumours". Langenbecks Arch Surg 391 (4): 322–9. doi:10.1007/s00423-005-0005-5. PMID 16402273.
  3. Pasquinelli G, Severi B, Martinelli GN, Santini D, Gelli MC, Tison V (April 1995). "Gastro-intestinal stromal tumors: an ultrastructural reinterpretation of the clear cell component". J. Submicrosc. Cytol. Pathol. 27 (2): 251–7. PMID 7757951.