Infectious complications have been known to be a major cause of morbidity and mortality in CLL patients who are predisposed to infections because of both the humoral immunodepression inherent to hematologic disease, which is related to stage and duration of CLL, and to further immunosuppression related to therapy. The majority of infections in CLL patients treated with alkilating agents is of bacterial origin. The immunodeficiency and natural infectious history of alkylator-resistant, corticosteroid-treated patients appears to have changed with the administration of purine analogs, which has been complicated by very severe and unusual infections and also more viral infections due to sustained reduction of CD4-positive T lymphocytes. The following introduction of monoclonal antibody therapies, in particular alemtuzumab, further increased the immunodepression, increasing also infections which appeared more often in patients with recurrent neutropenia due to chemotherapy cycles.
Epidemiological data regarding fungal infections in lymphoproliferative disorders are scarce. Italian SEIFEM group in a retrospective multicentre study regarding CLL patients reported an incidence of mycoses 0.5%; however, chronic lymphoproliferative disorders emerged as second haematological underlying disease after acute leukemia in a French study on aspergillosis; in particular CLL with aspergillosis accounted for a third of these chronic lymphoproliferative diseases presenting mould infection.