Primary squamous cell carcinoma of the duodenum
Primary small bowel squamous cell carcinoma is exceedingly rare, with 22 cases reported in the literature.
The duodenum is the most commonly site. Normally there are no squamous cells in the small bowel, but it is postulated that malignant transformation of heterotopic squamous cells (such as in a diverticulum), pluripotent stem cells, or squamous metaplasia may be responsible.
Given the exophytic, ulcerative appearance of the tumor, it may be that the tumor arose from an intestinal duplication.
Whole body PET/CT confirmed no other primary tumor or other sites of disease besides the hepatic segment 3 lesion.