Cholangiocarcinoma complicating secondary sclerosing cholangitis from cryptosporidiosis in an adult patient with CD40 ligand deficiency: case report and review of the literature.

A 43-year-old man with a hyper-immunoglobulin M syndrome due to CD40 ligand deficiency presented with insidious onset of recurrent diarrhoea and deranged liver function tests. Standard stool microscopy was repeatedly negative for cryptosporidia but immunofluorescent testing and polymerase chain reaction demonstrated the presence of infection eventually. Despite both paromomycin and nitazoxanide, he developed sclerosing cholangitis secondary to cryptosporidial infection. Whilst being considered for dual bone marrow and liver transplantation, he was found to have cholangiocarcinoma on imaging after three biopsies of a suspicious lesion. This is a rare complication of this combined immune deficiency predominantly in children that has not been reported previously in a long-term survivor with this condition.