19 February 2025
: Case report 
Extragastrointestinal Stromal Tumor Mimicking Appendicitis: A Case Study
Unusual clinical course, Challenging differential diagnosis, Rare coexistence of disease or pathology
Ricardo Martinez ABDEFG 1, Michael Lezcano ABDEFG 1, Jonak Randhawa ABDEFG 1, Shahryar Aijaz ABDEFG 1, Yara Al Mazouni ABDEFG 1, Ahmed Altamimi ABDEFG 2,3*, Norka Camacho-Perez ABDEFG 1, Feras Othman ABDEFG 4, Andrew M. O'Neill ACD 3, Joshua A. Simon BCD 3DOI: 10.12659/AJCR.944665
Am J Case Rep 2025; 26:e944665
Table 1. Follow-up of gastrointestinal stromal tumor (GIST) patients treated with surgery alone [19].
| Risk group | Recurrence risk evaluation method | Follow-up recommendation | ||
|---|---|---|---|---|
| Modified National Institutes of Health scheme | Armed Forces Institute of Pathology (AFIP) scheme | Prognostic heat maps | ||
| Very low risk | ≤2.0 cm, ≤5 mitoses/50 high power fields (HPFs), any tumor site | Group 1 | 0–10% | Likely cured by surgery. No regular follow-up |
| Low risk | 2.1–5.0 cm, ≤5 mitoses/50 HPFs, any tumor site | Group 2 | 0–10% | No follow-up; OR abdominal/pelvic computerized tomography (CT)/magnetic resonance imaging (MRI) annually for approximately 5 years |
| Intermediate risk | ≤2.0 cm, 6–10 mitoses/50 HPFs, gastric tumor OR 5.1–10.0 cm, ≤5 mitoses/50 HPFs, gastric tumor | Group 3a | 10–20% | Abdominal/pelvic CT/MRI annually for approximately 5 years, the first scan approximately 6–8 months after surgery |
| High risk | The rest of the patients; any patient with tumor rupture | Groups 3b, 4, 5, 6a, 6b | 30–100% | Abdominal CT/MRI 6-monthly for the first 5 years, then annually for the next 5 years (the total duration of follow-up is 10 years after surgery) |
| * Patients with a high estimated risk for GIST recurrence should be treated with adjuvant imatinib, and they are recommended to be followed up as shown in . The recommendations shown in apply only to high-risk patients whose GIST contains a mutation that confers imatinib resistance (notably exon 18 mutation D842V) or is wild-type for and . | ||||