Background: Rituximab is a monoclonal antibody that has been in use since 1997 as a method of combating non-Hodgkin lymphoma and chronic lymphocytic leukemia. Its effect on cellular cytotoxicity among B-cell lymphocytes has been extensively studied. Rituximab’s adverse effect profile is associated with acute infusion reactions or increased susceptibility to viral infections; however, the current literature indicates few relations to bacterial infections.
Methods and Results: A 69-year-old man with a history of treated Mycobacterium chelonae pneumonia had a condition diagnosed as chronic lymphocytic leukemia that had undergone Richter transformation to diffuse large B-cell non-Hodgkin lymphoma. He subsequently underwent 2 doses of rituximab therapy treatment. Two weeks later, he presented to his ambulatory care clinic with right forearm erythema, swelling, and increasing pain. The patient also complained of intermittent fevers, chills, and night sweats. A provisional diagnosis of cellulitis was made and basic antibiotic treatment was begun. After a month of worsening forearm swelling, erythema, and leukocytosis, the patient underwent irrigation and debridement of his wound. The patient’s condition continued to deteriorate with fevers, altered mental status, and weakness. He was noted to have both a diffuse miliary nodular pattern on thoracic computed tomography and subcentimeter miliary lesions on a magnetic resonance imaging scan of the brain. Subsequently, cultures of his forearm returned positive for Mycobacterium tuberculosis (MTB). The patient was started on traditional antimycobacterial therapy, and his clinical course improved with some persistent intermittent fevers. He has continued to receive MTB treatment, and rituximab has been withheld.
Conclusions: The most heavily publicized viral infection is reactivation of latent hepatitis B virus, with very little evidence of increased bacterial infections from rituximab use. There is some suggestion of increased risk for MTB infections, but this has not been reported in the literature. There is accumulating evidence supporting the concept that B-cell immunity does indeed play a role in defense against MTB, and B cells have been identified as having an influence on bacillary containment. With increasing studies indicating the importance of B cells on immunity and this recent documented case, physicians should remain vigilant in attempting to identify potential infectious complications and should open the discussion of whether pretreatment screening for MTB may be necessary before treatment with rituximab.