Hairy cell leukemia: Uncommon clinical features, unusual sites of involvement and some rare associations

Unusual clinical manifestations and associations with auto-immunity or other systemic disorders are uncommon clinical features of hairy cell leukemia (HCL). The exact prevalence of these rare associations is difficult to determine as they are mostly published as anecdotal case reports and generally not included in larger published series. This chapter deals with uncommon clinical manifestations and rare sites of involvement in HCL. It also summarizes the association with systemic hemato-oncological disorders as well as second malignancies, based on review of the relevant literature and from personal experience.