**Background:** Gastrointestinal stromal tumors (GISTs) are mesenchymal neoplasms arising from the interstitial cells of Cajal. While common in older adults (sixth to seventh decade), GISTs are rare in children, with only 0.4% of all GIST patients being under 20 years old and patients aged 8–20 comprising approximately 1.64% of all GIST cases. Over 80% of pediatric GISTs arise from the stomach, and the most common presenting symptom is anemia secondary to gastrointestinal bleeding. Endoscopic ultrasound (EUS) and EUS-guided fine needle aspiration (EUS-FNA) are well-established diagnostic tools in adults but experience in pediatric patients is limited. This report presents two pediatric cases of gastric GIST diagnosed using EUS and EUS-FNA.
**Methods:** Two cases are described from a single institution. Case 1: A 14-year-old male presented with 4 days of dizziness and dark stools. Physical exam showed pallor, tachycardia (124 bpm), and tachypnea (24 bpm). Laboratory findings: hemoglobin 7 g/dL, MCV 83.1 fL, reticulocyte count 3.8%, ferritin 10 ng/mL, and positive stool occult blood. He received two units of packed red blood cells. Initial CT did not clearly reveal a mass (retrospectively showed a possible antral mass without enhancement characteristics beyond normal gastric folds or ingested food) and showed no metastatic disease. Initial EGD revealed a submucosal mass in the gastric antrum with overlying ulceration; biopsies of stomach and duodenum showed no malignancy. The following day, EUS demonstrated a hypoechoic, subepithelial mass in the distal stomach originating from the fourth hypoechoic layer, and EUS-FNA was performed. Cytology showed a spindle and epithelioid neoplasm with uniform cellularity and bland nuclear features, most consistent with GIST. The patient underwent exploratory laparotomy and partial gastrectomy. Pathology confirmed a 3 cm × 2.5 cm × 2 cm firm submucosal mass, completely resected (0.7 cm from each margin). Immunohistochemistry: positive for DOG-1 and C-kit; negative for CK, S100, MSA, SMA, synaptophysin, and desmin. MIB-1 showed a low proliferation rate (mitotic rate <5/5 mm²). No adjuvant therapy was administered. No complications or signs of recurrence in the short postoperative period.
Case 2: An 11-year-old female presented with fatigue, pallor, dizziness, and abdominal pain. Physical exam showed pallor and a II/VI systolic ejection murmur. Laboratory findings: hemoglobin 6.9 g/dL, MCV 70 fL, reticulocyte count 3.8%, ferritin 3 ng/mL, and heme-positive stool. EGD revealed bleeding ulcers associated with gastric tumors. EUS-FNA cytology was consistent with multifocal GIST (details of EUS findings not available due to predating electronic medical records). She underwent distal gastrectomy with Billroth I gastroduodenostomy. Pathology confirmed GIST with five nodules clustered together, the largest 5 cm in diameter. Microscopy showed mixed epithelioid and spindle cell morphology. C-kit positive, CD34 negative. Mitotic count was low at 30 mitoses per 50 high-powered fields. Surgical margins were free of tumor; no nodal metastases. No adjuvant therapy. Follow-up CT showed no local recurrence or metastatic disease. At 1-year follow-up, she had iron deficiency anemia with negative stool hemoccult; EUS-FNA revealed gastric polyps but no GIST. Anemia resolved with oral iron and birth control pills. EUS was subsequently used multiple times to scan for GIST recurrence or other GI pathologies. She remains disease-free 14 years from original diagnosis.
**Key Results:** Both patients were successfully diagnosed with gastric GIST using EUS and EUS-FNA. Both underwent complete surgical resection with negative margins. Case 1 had no recurrence in short-term follow-up. Case 2 had no recurrence over 14 years of follow-up, and EUS was safely used for surveillance.
**Clinical Implications:** This report adds to the limited evidence that EUS and EUS-FNA are safe, feasible, and accurate diagnostic tools for pediatric patients with suspected gastric GIST. EUS can also be used for periodic surveillance for recurrent disease. Clinicians should consider GIST in the differential diagnosis of pediatric patients presenting with unexplained anemia and a gastric submucosal mass, and EUS-FNA should be considered as a diagnostic modality.