SALL4 positive fetal gut-like adenocarcinoma of the duodenum.

Fetal gut-like adenocarcinoma is a rare carcinoma, previously reported in the stomach, which features clear cytoplasm cell papillotubular carcinoma and morphology similar to the fetal gut epithelium. SALL4, a novel marker for progenitor-type tumors, has shown high expression in fetal gut-like adenocarcinoma, which may represent oncofetal protein expression and fetal differentiation. Herein, we report the first case of fetal gut-like adenocarcinoma of the duodenum. An 81-year-old man was admitted on account of jaundice. A deeply ulcerating duodenal tumor formed a 4 cm periampullar mass. Pancreatoduodenectomy with lymphadenectomy was performed. Funicular and solid growth of clear cytoplasmic cells that resembled the fetal gut epithelium formed a poorly differentiated adenocarcinoma. Lymph node metastasis was present. Immunohistochemistry analysis showed diffuse nuclear positivity for SALL4. For postoperative therapy, S-1 was administered. The patient is alive with no recurrence, 83 months postoperatively. This case may contribute to further elucidate the disease entity of SALL4 positive, fetal-type carcinomas.