Jejunal adenocarcinoma with isolated mesorectal metastasis: a case report of a rare entity

Small bowel (SB) neoplasms are rare and often diagnosed at advanced stages, commonly presenting with obstruction or obscure gastrointestinal bleeding (OGB). An 83-year-old man presented with anemia and hematochezia. Imaging revealed an 8 cm SB mass and a 5 cm rectal lesion initially suggestive of GIST. Biopsy confirmed adenocarcinoma. Due to recurrent bleeding, the patient underwent segmental enterectomy and Hartmann's procedure. Histology showed jejunal mucinous adenocarcinoma with mesorectal metastasis (pT4N0M1). Despite adjuvant chemotherapy and hemostatic radiotherapy for pelvic recurrence, the patient died 7 months postoperatively. SB tumors should be considered in OGB with anemia. Adenocarcinoma is the most common type. Surgery was chosen due to refractory anemia and resectable oligometastatic disease in the mesorectum. Jejunal adenocarcinoma is difficult to diagnose. Surgery remains the main treatment and selected resection of distant metastases may improve survival. Mesorectal involvement is rare and presents additional management challenges.