Small Intestinal Carcinoma

Gross examination of the colectomy specimen revealed more than 20 large polyps measuring up to 4 cm. Histopathological analysis demonstrated colonic serrated polyposis without evidence of invasive malignancy, wall infiltration, or lymph node involvement, with clear surgical margins.

The patient recovered uneventfully with resolution of bleeding and normalization of hemoglobin. This case highlights the importance of considering small bowel GIST in unexplained melena and severe anemia and demonstrates the curative potential of timely surgical resection in localized low-risk disease.

P=N/A, N=750, Active, not recruiting, M.D. Anderson Cancer Center | Trial completion date: Jan 2026 --> Jan 2028 | Trial primary completion date: Jan 2026 --> Jan 2028

This case highlights an unusual presentation of a rare malignancy in a duodenal neuroendocrine tumor identified during evaluation of iron deficiency anemia. It emphasizes the importance of comprehensive endoscopic assessment and targeted biopsy in patients with unexplained anemia, including consideration of uncommon gastrointestinal neoplasms.

This case represents a rare duodenal MGT confirmed by histopathology and immunohistochemistry, with novel FOXP1 and KDM5A mutations identified for the first time. These findings broaden the molecular spectrum of MGT and highlight the importance of integrating molecular profiling into the diagnosis and management of rare tumors, while surgical resection remains the cornerstone of therapy.

The postoperative course was complicated by sepsis, respiratory failure, and prolonged ileus. This case highlights the importance of considering primary gastrointestinal lymphoma in the differential diagnosis of bowel perforation and acute surgical abdomen, particularly in elderly patients presenting emergently.

This case underscores the role of immunotherapy in POLE-mutated tumors regardless of the site of origin and highlights the potential usefulness of molecular profiling in rare malignancies. In line with the agnostic approach used for microsatellite instability, molecular-driven clinical trials should be prioritized over histology-based studies to optimize treatment strategies for these orphan diseases.

P2, N=798, Active, not recruiting, National Cancer Institute (NCI) | Trial primary completion date: May 2027 --> May 2026

P=N/A, N=131, Completed, Fondazione Policlinico Universitario Agostino Gemelli IRCCS

P=N/A, N=845, Active, not recruiting, Sidney Kimmel Comprehensive Cancer Center at Thomas Jefferson University | Recruiting --> Active, not recruiting | Trial completion date: Apr 2026 --> May 2031 | Trial primary completion date: Apr 2026 --> Aug 2028

Histopathology established a high-grade, multifocal GIST (pT4(m)N0) with spindle-to-epithelioid morphology, increased mitotic activity, necrosis, strong CD117 and DOG1 positivity, and an elevated Ki-67 labeling index. This case highlights the characteristic radiologic features of ruptured GIST and demonstrates close radiologic-pathologic concordance in an aggressive presentation.

Pathology thus represented the diagnostic cornerstone. This case contributes to the limited literature describing MRI features of small bowel leiomyosarcoma presenting with adult intussusception and underscores the importance of a multimodal diagnostic approach, in which MRI serves as an adjunct to CT, while histopathology remains essential for definitive diagnosis.