title: False-positive cerebrospinal fluid cryptococcus antigen in Libman-Sacks endocarditis.
abstract: BACKGROUND
  Cryptococcus meningoencephalitis is a serious opportunistic infection associated with high morbidity and mortality in immunocompromised hosts, particularly patients with advanced AIDS disease. The diagnosis is established through cerebrospinal fluid (CSF) cryptococcus antigen detection and cultures. Cryptococcus antigen testing is usually the initial test of choice due its high sensitivity and specificity along with the quick availability of the results.
  
  
  METHODS
  We hereby report a case of a false-positive CSF cryptococcus antigen assay in a patient with systemic lupus erythematosus presenting with acute confusion. While initial CSF evaluation revealed a positive cryptococcus antigen assay, the patient's symptoms were inconsistent with cryptococcus meningoencephalitis. A repeat CSF evaluation, done 3 days later, revealed a negative CSF cryptococcus antigen assay.
  
  
  CONCLUSIONS
  Given the patient's active lupus disease and the elevated antinuclear antibody titers, we believe that the initial positive result was a false positive caused by interference from autoantibodies.
authors.affiliation: Department of Internal Medicine, Henry Ford Hospital, 2799 W Grand Blvd, Detroit, MI, 48202, USA. iisseh1@hfhs.org.
authors.forename: Iyad N
authors.initials: IN
authors.lastname: Isseh
authors.affiliation: Department of Internal Medicine, Henry Ford Hospital, 2799 W Grand Blvd, Detroit, MI, 48202, USA.
authors.forename: Kassem
authors.initials: K
authors.lastname: Bourgi
authors.affiliation: Department of Internal Medicine, Henry Ford Hospital, 2799 W Grand Blvd, Detroit, MI, 48202, USA.
authors.forename: Asaad
authors.initials: A
authors.lastname: Nakhle
authors.affiliation: Department of Internal Medicine, Henry Ford Hospital, 2799 W Grand Blvd, Detroit, MI, 48202, USA.
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Ali
authors.affiliation: Division of Infectious Diseases, Henry Ford Hospital, 2799 W Grand Blvd, Detroit, MI, 48202, USA.
authors.forename: Marcus J
authors.initials: MJ
authors.lastname: Zervos
mesh_terms: D000946:Antigens, Fungal / Q000134:cerebrospinal fluid*; D003453:Cryptococcosis / Q000150:complications / Q000175:diagnosis* / Q000382:microbiology; D003454:Cryptococcus / Q000276:immunology*; D004696:Endocarditis / Q000150:complications / Q000175:diagnosis* / Q000382:microbiology; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000150:complications*; D008875:Middle Aged
chemical_list: D000946:Antigens, Fungal
keywords: Cryptococcus antigen; Cryptococcus meningoencephalitis; Libman–Sacks endocarditis; Systemic lupus erythematosus