S6237 Hidden in Plain Sight: Jejunal Adenocarcinoma Presenting as Nonspecific GI Symptoms in a Low-Risk Patient

Introduction: Small bowel adenocarcinoma (SBA) is a rare malignancy accounting for <2% of gastrointestinal (GI) cancers. Its nonspecific presentation often delays diagnosis, limiting treatment options and worsening prognosis. We present a rare case of jejunal SBA in a healthy middle-aged woman with full remission following prompt surgical and chemotherapeutic management. Case Description/Methods: A 52-year-old woman with no significant medical history presented with 2 months of nausea, vomiting, and 40-pound unintentional weight loss. Workup for H. pylori and gastroesophageal reflux disease was unrevealing. She was admitted due to worsening symptoms and inability to tolerate oral intake. Computed tomography imaging revealed a high-grade small bowel obstruction in the mid-distal jejunum with severe proximal bowel dilation. Laparoscopy with segmental resection identified a 3.5 cm jejunal mass. Pathology confirmed moderately differentiated adenocarcinoma invading the serosa (T3N0M0, Stage IIA). MMR testing showed intact MLH1, PMS2, MSH2, and MSH6 expression, ruling out Lynch syndrome. She completed 6 cycles of mFOLFOX with no recurrence at 5-year follow-up. Discussion: SBA often presents late with vague GI symptoms, delaying diagnosis and worsening prognosis. Despite a healthy baseline and lack of risk factors, this patient’s case emphasizes that SBA should be considered in persistent unexplained GI complaints. Negative MMR ruled out hereditary cancer, though her presentation raised concern for Lynch syndrome. Complete remission suggests that early surgical resection combined with adjuvant chemotherapy can significantly improve long-term outcomes. This case underscores the need for early imaging in persistent GI symptoms, even in low-risk patients. Increased clinical suspicion and expedited workup may improve early SBA detection, optimize treatment, and potentially enhance survival rates.