A 46-year-old male patient with Crohn’s disease and a small 1 cm intrabdominal desmoid-type fibromatosis (DTF) was found to have a CTNNB1 mutation variant c.133T>C p.(Ser45Pro) (Frequency: 21.1% of the 3287 NGS reads) in the N-terminus of the protein. The gene discussed is CTNNB1; the disease is desmoid tumor.