Combining two or more skin biopsy sites resulted in sensitivity exceeding 92%, providing improved diagnostic accuracy over cerebrospinal fluid analysis in detecting prion diseases, according to a recent study.
In the study, published in JAMA Neurology, researchers compared the diagnostic accuracy of multisite skin biopsies vs cerebrospinal fluid (CSF) in detecting prion diseases (PRDs) using the real-time quaking-induced conversion (RT-QUIC) assay. The diagnostic study involved 101 patients with PRDs and 23 control patients, utilizing a total of 415 skin samples and 160 CSF samples.
The positive rates for single-site skin biopsies using the RT-QUIC assay were as follows: 84.9% for the near-ear area (79/93 samples), 80.8% for the upper arm (21/26 samples), 83.7% for the lower back (77/92 samples), and 84.8% for the inner thigh (78/92 samples). In comparison, CSF samples showed a positive rate of 75.5% (71/94 samples).
However, when combining two or three skin biopsy sites, diagnostic sensitivity improved significantly, with positivity rates exceeding 92.1% compared with 75.5% for CSF. Testing skin samples at multiple dilutions further increased diagnostic accuracy, demonstrating that multisite skin biopsies may offer superior sensitivity compared with CSF analysis alone.
In the confirmatory cohort, single-site skin biopsies showed a sensitivity of 79.1% (34/43 cases), while CSF analysis had a sensitivity of 72.1% (31/43 cases).
Full disclosures can be found in the published study.