Cholangiocarcinoma in a 33-year-old male with CD40L deficiency and pre-papillary bile duct stenosis.

X-linked hyper IgM-syndrome caused by CD40L deficiency is a rare primary immunodeficiency. Affected male individuals who reach adulthood often develop sclerosing cholangitis. Here, we report the case of a 33-year-old patient with long-standing solitary pre-papillary bile duct stenosis but without further signs of sclerosing cholangitis, who developed distal cholangiocarcinoma. Given the increased risk of malignancy in these patients, this case highlights, that individuals with CD40L deficiency should be screened for the presence of cholangiopathy and be closely monitored for any signs of disease progression, development of hepatobiliary dysplasia or malignancy.