Multifocal Peritoneal Mucinous Carcinoma Presenting as Small Bowel Obstruction: A Case Report.

Mucinous carcinoma involving the small bowel is a rare cause of intestinal obstruction and a diagnostically challenging entity. When multifocal mucinous deposits involve the small bowel and abdominal wall, establishing the diagnosis and identifying the site of origin requires an integrated clinicopathological approach. We present a case of a 42-year-old woman who presented with acute small bowel obstruction. Laparotomy revealed multiple lesions involving the ileum and cecal region. The primary obstructing lesion was located in the mid-ileum with proximal bowel dilatation and distal collapse. Additional non-obstructing lesions were identified approximately one meter distal to the first lesion and near the ileocecal valve, along with a cecal lesion adherent to the right fallopian tube. Histopathological examination demonstrated multifocal mucinous carcinoma with abundant extracellular mucin pools containing malignant epithelial cells infiltrating the intestinal wall and fibroadipose tissue. This case highlights the diagnostic challenge posed by multifocal mucinous carcinoma presenting as bowel obstruction. Awareness of this rare presentation is important for surgical decision-making and postoperative oncologic evaluation.