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A6489 - HIV False Positivity Due to Sarcoidosis
Author Block: J. Lio1, G. Barmaimon2, P. S. Patrawalla3; 1Internal Medicine, Mount Sinai Beth Israel, New York, NY, United States, 2Pulmonary and Critical Care Medicine, Mount Sinai St Luke's, New york, NY, United States, 3Pulmonary and Critical Care Medicine, Mount Sinai Beth Israel, New York, NY, United States.
Innumerable randomly distributed pulmonary nodules with hilar and paratracheal lymphadenopathy are a common reason for pulmonary consult. While the differential is broad, human immunodeficiency virus (HIV) status strongly influences the suspected conditions and the need to rule out infectious etiologies is more pressing. Here we present a case of the above with falsely positive HIV testing based on screening antibody. A 51-year-old Swiss man who had been monogamous with his wife of eight years presented with an incidental finding of innumerable randomly distributed subcentimeter pulmonary nodules along with paratracheal and precarinal lymphadenopathy, the largest in size being 4.1 by 2.3 cm. He had initially seen his primary care physician for right leg cramping, leading to an MRI revealing right popliteal arterial aneurysm. He was sent to the ED for management, where CT angiography revealed pulmonary anomalies. His wife recalled him having a dry cough for several years, which the patient himself had not noticed, but the patient was otherwise asymptomatic. Initial work up revealed normal serum ACE levels and HIV positivity based on detection of p24 antigen. CD4 was 157 but repeat p24 antigen testing, HIV antibody, and viral load were undetectable. The patient eventually underwent bronchoscopy with ultrasound guided FNA of the subcarinal lymph nodes revealing noncaseating granulomas. AFB, fungal, and bacterial culture and smears of the sample failed to reveal any organism. The patient was concluded to have asymptomatic pulmonary sarcoidosis and p24 antigen reactivity unrelated to HIV, due to his autoimmune condition. In the community setting, rapid screening HIV tests are over 99.3-99.91% specific. The fourth generation rapid HIV test relies on detection of p24 antigen, which allows for detection of HIV infection before seroconversion, as well as antibodies to HIV-1 and HIV-2. These tests require confirmation testing with quantitative RNA testing. Falsely positive HIV testing using the p24 antigen has been reported in a handful of previous case reports including case reports of a woman with lupus nephritis, a patient with cross reactivity due to EBV infection, and a patient with malignancy. Our patient, who had low pretest probability of HIV, had p24 antigen reactivity. Based on these initial test results, infectious etiologies of his pulmonary findings were highest on the differential. The initial reactivity to p24 was likely due to his sarcoidosis and did not represent true infection.