General Surgery · Year 3 · from General Surgery

Case 3: Gastrointestinal Stromal Tumor (GIST)

Patient Demographics

  • Age: 56 years
  • Sex: Female
  • Occupation: Bank manager

Chief Complaint

"I was told I have a mass in my stomach found on a CT scan."

History of Present Illness

The patient was recently evaluated for vague abdominal discomfort and bloating. An outpatient CT scan revealed an incidental gastric mass. She reports mild, intermittent epigastric fullness but no significant pain. She denies nausea, vomiting, weight loss, or GI bleeding. Her symptoms have been stable for several months. She has no history of peptic ulcer disease.

Past Medical History

  • Hyperlipidemia
  • Anxiety
  • No prior surgeries

Medications

  • Atorvastatin 20 mg daily
  • Sertraline 50 mg daily

Physical Examination

  • Vitals: Normal
  • General: Well-appearing woman, normal body habitus
  • Abdomen: Soft, non-tender, no palpable masses
  • No lymphadenopathy

Diagnostic Workup

CT Abdomen/Pelvis:

  • 4.5 cm well-circumscribed, enhancing mass arising from the greater curvature of the stomach
  • Exophytic growth pattern
  • No surrounding invasion
  • No liver metastases or lymphadenopathy

Upper Endoscopy:

  • Submucosal mass in the gastric body with normal overlying mucosa
  • Smooth, round protrusion into the lumen
  • "Pillow sign" positive (compressible)
  • Mucosa intact - not biopsied

Endoscopic Ultrasound (EUS):

  • 4.3 cm hypoechoic mass arising from the fourth layer (muscularis propria)
  • Homogeneous internal appearance
  • No cystic areas or necrosis
  • Features consistent with GIST
  • EUS-guided FNA performed

FNA Results:

  • Spindle cell neoplasm
  • CD117 (c-KIT): Positive
  • DOG1: Positive
  • Consistent with gastrointestinal stromal tumor (GIST)

Diagnosis

Gastric GIST, 4.5 cm

Risk Stratification

Using Miettinen criteria for gastric GIST:

  • Size: 4.5 cm (>2 cm, ≤5 cm)
  • Mitotic rate: To be determined on final pathology
  • Location: Stomach (favorable)
  • Estimated recurrence risk: Low to intermediate

Surgical Planning

  • Complete surgical resection indicated
  • Goal: R0 resection with negative margins
  • Lymphadenectomy not required (GISTs rarely metastasize to lymph nodes)
  • Wedge resection vs. limited gastrectomy depending on location

Operative Procedure

Laparoscopic wedge resection of gastric GIST:

  • Mass identified on greater curvature
  • Adequate margins around tumor
  • Wedge resection using laparoscopic staplers
  • Tumor removed in endoscopic retrieval bag (avoid rupture)
  • No spillage

Final Pathology

  • GIST, 4.5 cm
  • Spindle cell type
  • Mitotic rate: 3/50 HPF (low)
  • Margins: Negative (R0)
  • CD117 positive, DOG1 positive
  • Mutation analysis: KIT exon 11 mutation

Risk Assessment (Post-resection)

  • Modified NIH criteria: Low risk
  • Recurrence risk: <5% at 5 years

Adjuvant Therapy Decision

  • Given low-risk classification, adjuvant imatinib NOT recommended
  • Close surveillance recommended

Surveillance Plan

  • CT abdomen/pelvis every 6 months for 3 years, then annually for 5 years
  • No role for routine endoscopy unless symptoms

Teaching Points

  1. GISTs arise from interstitial cells of Cajal
  2. Most common mesenchymal tumor of the GI tract
  3. c-KIT (CD117) and DOG1 are diagnostic markers
  4. Risk stratification based on size, mitotic rate, and location
  5. Surgery is primary treatment; lymphadenectomy not needed
  6. Imatinib (tyrosine kinase inhibitor) for high-risk or metastatic disease
  7. Avoid tumor rupture during surgery (seeds peritoneum)

Clinical Image

Image Description: Endoscopic ultrasound image demonstrating a well-circumscribed, hypoechoic mass arising from the fourth layer (muscularis propria) of the gastric wall, characteristic of a gastrointestinal stromal tumor (GIST).

Attribution: Image from Wikimedia Commons. Source: https://commons.wikimedia.org/wiki/Category:Gastroenterology

All cases for this lecture as Markdown