View Abstract

A5413 - Cryptococcus Gattii: Not Just a Disease of the Immunocompetent. A Rare Case of Pulmonary Cryptococcus in an Individual with Chronic Lymphocytic Leukemia on Obinutuzumab
Author Block: J. Stevens1, C. Dedeaux Ii2, G. Allada3; 1Pulmonary and Critical Care, Oregon Health and Sciences University, Portland, OR, United States, 2Division of Internal Medicine, Oregon Health and Sciences University, Portland, OR, United States, 3Pulmonary and Critical Care, Oregon Health and Science University, Portland, OR, United States.
Cryptococcus gattii is an environmental fungus found growing in tree bark, and soil and is a known endemic pathogen in primarily tropical and subtropical regions of the world. C.gatti has more recently has become established in the Pacific Northwest region of the United States following an outbreak on Vancouver Island, British Columbia, Canada in 1999. The primary site of infection is the lungs leading to pneumonia or cryptococcomas but it can also disseminate to other organs including the central nervous system causing meningioencephalitis. While this primarily occurs in immunocompetent hosts, C. gattii has been increasingly identified in immunosuppressed individuals.
A 58 year old woman presented to hematology clinic with several months of fatigue, dyspnea on exertion, dry cough and right sided pleuritic chest pain was found to have multiple peripheral pulmonary consolidations on routine restaging chest CT. She has a complex past medical history including chronic lymphocytic leukemia for which she completed six cycles of obinutuzumab two months prior to presentation, and an admission four months prior to presentation for critical digit ischemia due to cryoglobulinemic vasculitis treated with an ongoing, prolonged steroid taper, and one dose of rituximab. She also has ongoing tobacco use, and chronic obstructive lung disease.
She was admitted for expedited workup of her pulmonary findings which included a broad differential diagnosis of infection, vasculitis and neoplastic etiologies. She underwent a bronchoscopy with bronchoalveolar lavage which was significant for medium-sized yeast with capsules on silver stain suggestive of Cryptococcus which was further supported by a positive serum cryptoccoccal antigen. A lumbar puncture and head CT were negative for central nervous system involvement and she was subsequently started on oral fluconazole. Bronchoalveolar fungal cultures eventually grew Cryptococcus gattii species.
This is the first known reported case of a patient with pulmonary Cryptococcus gattii with CLL on obinutuzumab and concurrent corticosteroid use. Obinutuzumab is a humanized anti-CD20 monoclonal antibody which leads to B cell depletion. Clearance of C.gattii in exposed individuals requires an intact innate and adaptive immune system with T cell responses having a known key role in the control of infection both in clinical and experimental models. There is emerging evidence that B cell and antibody responses are a significant part of the host defense in anticryptococcal immunity which may identify patients with B cell deficiencies at higher risk for cryptococcal disease