[The Kveim-Siltzbach test in sarcoidosis]

Sarcoidosis diagnosis remains challenging due to variable clinical presentations and nonspecific symptoms. Traditional diagnostic tools include imaging and biopsy, which can be invasive. The Kveim-Siltzbach test has been proposed as a non-invasive alternative. Prior research has shown mixed results regarding its diagnostic accuracy. No prior work had resolved its performance in specific sarcoidosis subtypes or stages. This gap motivated an evaluation of the test's diagnostic usefulness in a clinical setting. The test involves injecting a sarcoid spleen antigen and observing for a delayed hypersensitivity reaction. It was already known that the test has high specificity in some populations. However, its sensitivity and stage-specific performance remained unclear.

This study aimed to assess the diagnostic performance of the Kveim-Siltzbach test in sarcoidosis patients. The researchers focused on sensitivity and stage-specific variability. They sought to determine whether the test could reliably distinguish sarcoidosis from other conditions. The motivation was to evaluate its utility in non-invasive diagnosis. The study was conducted in a clinical setting with a defined patient cohort. The researchers reviewed prior experience in their centers to establish baseline expectations. They also aimed to validate the antigen lots used in the test. The goal was to provide evidence supporting the test's diagnostic value.

The Kveim-Siltzbach test was performed on 79 patients suspected or diagnosed with sarcoidosis. The study spanned from 1977 to 1988 and was conducted in collaboration with a reference laboratory. Sarcoid spleen suspensions were prepared in the Standards Laboratory for Serological Reagents in London. The antigen lots used included K12, K12 1/2, K32, K41, K42, K42 1/2, and K50 of the Colindale antigen. Test positivity was assessed using Siltzbach’s established criteria. No control group was included, as the study focused on diagnostic accuracy in a clinical cohort. Patients were categorized based on sarcoidosis stage and clinical features. Results were analyzed for sensitivity and stage-specific performance.

The global sensitivity of the Kveim-Siltzbach test was 78% (95% CI: 67.8–86.9). Positivity was highest in subacute sarcoidosis at 84%. Chronic sarcoidosis showed a lower positivity rate of 61%. Patients with radiologic stage I had 84% positivity, while stage III had 62%. Extrathoracic sarcoidosis (stage 0) had a positivity rate of 57%. No significant association was found between test positivity and angiotensin-converting enzyme (ACE) levels (p = 0.575). The test showed consistent results across different antigen lots. These findings suggest the test is a reliable diagnostic tool in most sarcoidosis cases.

The Kveim-Siltzbach test demonstrated high sensitivity in diagnosing sarcoidosis. The authors propose that it is a useful non-invasive diagnostic method. The test performed best in subacute and early-stage sarcoidosis. Chronic and extrathoracic cases showed lower positivity rates. No correlation was found with serum ACE levels, suggesting independent diagnostic value. The test’s high specificity in other studies supports its clinical utility. The authors suggest it can aid in confirming sarcoidosis without invasive procedures. These findings make the test a valuable addition to diagnostic protocols.