Systemic Mastocytosis Causing Refractory Pruritus in a Liver Disease Patient.

Systemic mastocytosis (SM) results from clonal, neoplastic proliferation of abnormal mast cells. Patients become susceptible to itching, urticaria, and anaphylactic shock, which occurs due to histamine release from mast cells. SM may coexist alongside other systemic diseases, thus confounding the overall clinical presentation. We discuss a 23-year-old woman with refractory pruritus, which was initially attributed to primary sclerosing cholangitis but had a nonresponse to antihistaminics, ursodiol, and cholestyramine. Concurrent evaluation for polyarthritis revealed increased uptake in the proximal femur on a bone scan, and subsequent bone marrow biopsy revealed indolent SM, and this was understood to be the cause of her intractable pruritus.