Sarcomatoid Carcinoma of the Ileum Mimicking a Gastrointestinal Stromal Tumor (GIST) Presenting With Primary Subfertility: A Report of a Rare Case.

Sarcomatoid carcinoma (SCA) is a rare and aggressive malignancy characterized by the coexistence of epithelial and mesenchymal components. While it has been described in various organs, SCA of the ileum is exceptionally rare, with only handful of cases reported in the literature to date. We report a case of a 38-year-old woman presenting with primary subfertility and episodic lower abdominal pain, initially attributed to possible adenomyosis. During subfertility evaluation with a laparoscopic dye test, an incidental polypoidal growth was detected in the distal ileum. Contrast-enhanced computed tomography (CECT) revealed a heterogeneously enhancing mass in the right iliac fossa, suspected to be a gastrointestinal stromal tumor (GIST). Following multidisciplinary team discussions, surgical excision was performed with a laparoscopic assisted right hemicolectomy. Histopathological analysis confirmed a biphasic tumor with carcinomatous and sarcomatous components, consistent with SCA. Evaluation with immunohistochemical markers further narrowed down differential diagnoses. Postoperatively, the patient developed metastatic progression, as evidenced by peritoneal masses and an abdominal wall deposit on repeat CECT. She subsequently underwent adjuvant chemotherapy. SCA of the ileum poses significant diagnostic challenges due to nonspecific clinical features and its rarity. This case underscores the diagnostic complexities and therapeutic challenges of ileal SCA. Collaborative research is essential to develop effective treatment strategies for this rare malignancy.