%0 Case Reports
%T False-negative cerebral spinal fluid cryptococcal antigen lateral flow assay due to postzone phenomenon in a patient with disseminated cryptococcal disease: a case report.
%A Xu L
%A Mo YJ
%A Weng XB
%J J Int Med Res
%V 51
%N 3
%D Mar 2023
%M 36883444
%F 1.573
%R 10.1177/03000605231156767
%X This report presents the case of false-negative cerebral spinal fluid (CSF) cryptococcal antigen (CrAg) lateral flow assay (LFA) in a HIV-positive 25-year-old male. The patient presented with headache, nausea and vomiting for 5 days and syncope for 1 day. An initial CSF CrAg LFA test was negative, but a 1:4 dilution of the CSF was weakly positive and a 1:8 dilution was positive. A serum cryptococcal antigen test was weakly positive. Cultures of blood and CSF were all positive for Cryptococcus neoformans. The explanation for the false-negative CSF CrAg LFA test is that the antigen concentration was too high causing the postzone phenomenon.