Pancreatic desmoid tumor in a 4-year-old male with hemihypertrophy

•Desmoid tumors, especially cystic lesions, are rare and poorly characterized.•Desmoid tumors in patients with hemihypertrophy have never been reported.•Surgeons should consider desmoid tumors in cases of pancreatic cystic findings.

We report the first case of a pancreatic desmoid tumor detected during follow-up for hemihypertrophy in a 4-year-old boy. Hemihypertrophy is a rare disorder in which one side of the body grows more than the other, causing asymmetry, and well-known complications include embryonal tumors. However, there has been no report of desmoid tumors in patients with hemihypertrophy, and these tumors are rare and poorly characterized in the literature, especially the cystic variant. For this patient, the lesion was diagnosed as a desmoid tumor based on immunostaining positive for beta-catenin and mutation of the beta-catenin gene (CTNNB1). This case suggests that desmoid tumors should be considered a possible etiology of pancreatic cystic lesions in patients with hemihypertrophy.