Incidence and significance of abdominal lymphadenopathy in hairy cell leukaemia.

We have investigated the incidence and significance of abdominal lymphadenopathy in hairy cell leukemia (HCL) by routinely CT scanning 88 patients. These included 70 men and 18 women with a median age of 51 years (range 25-83). Abdominal CT scans were performed at diagnosis in 29 patients and in 59 during the course of the disease. Abdominal lymphadenopathy was documented in 25 patients (28%) overall; the incidence of abdominal lymphadenopathy was higher in relapse (56%) than at diagnosis (17%). All patients with lymphadenopathy had bone marrow disease. There is no association with age or sex but lymphadenopathy tends to be more common in patients with long-standing disease (median duration of disease 6 years v one year in those without nodes) and in patients with bulky disease, particularly in the relapse group (splenomegaly/splenectomy in 95% vs 40%). The presence of abdominal nodes is also associated with relative resistance to treatment, with more treatment failures and fewer complete responses seen in this group. Most patients with lymphadenopathy had large, immature-looking hairy cells present in both the bone marrow and lymph nodes, when these were examined. Abdominal lymphadenopathy in HCL is more common than previously recognised, particularly in relapsed patients, and is always associated with active disease. The presence of large hairy cells and the relative resistance to treatment suggest that this phenomenon represents a form of transformation of the disease. Longer follow up is required to confirm this.