Abstract: This article reports the management of a 59-year-old male patient with adenocarcinoma of the proximal jejunum.The patient was admitted to the hospital with epigastric distension and pain in February, and was referred to our hospital after small enteroscopy from an outside hospital revealed an irregular peripheral neoplasm in the proximal jejunum, which was diagnosed as adenocarcinoma pathologically.After admission, CT examination of small intestine was completed, and jejunectomy was performed on April 10, 2025 under general anesthesia.Postoperative pathology showed moderately differentiated adenocarcinoma, with the cancer cells penetrating into the lamina propria and reaching the surrounding adipose tissue, but without metastasis.Adenocarcinoma of the small intestine is rare and the early symptoms are hidden, which may lead to delayed diagnosis and affect the prognosis.

Key words: primary small bowel adenocarcinoma; jejunum; jejunostomy; diagnosis; treatment