Hidden in Plain Sight: Multifocal Asymptomatic Small Bowel Neuroendocrine Tumor Discovered During Robotic Excision of Incidentally Found Mesenteric Mass.

Neuroendocrine tumors (NETs) of the small bowel are uncommon, typically slow-growing neoplasms that may remain asymptomatic until reaching advanced stages. We present the case of a 69-year-old male with multiple comorbidities who was referred for evaluation of an incidentally identified mesenteric lesion on computed tomography (CT). Preoperative imaging revealed a 5 × 3.6 × 4.3 cm node-like mass within the mesentery. During robotic exploration, this lesion was identified along with two additional previously undetected small-bowel NETs. The patient underwent small bowel resection with en bloc removal of the mesenteric mass, and his postoperative course was uneventful. Final pathology demonstrated multifocal, well-differentiated NET with 9 of 20 lymph nodes positive for metastatic involvement. This case emphasizes important diagnostic and therapeutic considerations in the management of small-bowel NETs. Cross-sectional imaging can underestimate the true extent of disease, as multifocal tumors are common and may go undetected preoperatively. Complete surgical resection with negative margins remains the primary treatment modality and provides the best opportunity for long-term disease control. Minimally invasive and robotic approaches facilitate comprehensive intraoperative evaluation while preserving bowel length and vascular integrity. Early identification and definitive resection are critical, as untreated NETs can progress to complications such as mesenteric fibrosis, bowel obstruction, or metastatic spread despite their typically indolent course. This case highlights the importance of maintaining a high index of suspicion and performing careful intraoperative assessment when evaluating seemingly isolated mesenteric masses, given the potential for underlying multifocal disease.