New tissue scoring model boosts accuracy of IgG4-RD diagnosis
System provides standardized tool to complement existing diagnostics
Written by |
A new scoring system that standardizes how tissue samples are evaluated under a microscope for IgG4-related disease (IgG4-RD) may help doctors diagnose the body-wide, immune-mediated disease more accurately and consistently, a study suggested.
The system assigns numerical scores to multiple microscopic features in patients’ tissue samples, providing a “standardized, reproducible tool for IgG4-RD diagnosis” that enhances the objectivity and consistency of tissue evaluation and may serve “as a valuable complement to existing diagnostic frameworks for routine clinical practice,” the researchers wrote.
The study, “Development and clinical application of a histopathology-based pathological scoring system for IgG4-related disease,” was published in the Annals of Diagnostic Pathology.
IgG4-RD occurs when immune cells, particularly plasma cells producing a type of antibody called IgG4, infiltrate the body’s tissues. This leads to inflammation, tissue scarring (fibrosis), and the formation of tumor-like masses and enlargements that can affect virtually any organ, causing a wide range of IgG4-RD symptoms.
Current diagnostic guidelines lack ‘standardized, quantitative system’
Diagnosing IgG4-RD usually requires combining information from a patient’s symptoms, imaging scans, blood tests, and — most important — histopathology, the examination of a tissue sample under a microscope.
“However, the microscopic evaluation of IgG4-RD currently lacks a universally accepted, standardized quantitative system,” the researchers wrote.
Instead, current diagnostic guidelines rely on a combination of characteristic qualitative features — such as a distinctive swirling pattern of scar-like tissue and inflammation that can narrow or block small veins — and semi-quantitative measures, such as determining whether the number or proportion of IgG4-producing plasma cells exceeds established thresholds.
Because findings may vary among patients and require expert interpretation, this approach can lead to diagnostic uncertainty, particularly in atypical cases or when tissue samples are small.
A team of researchers in China set out to develop a quantitative histopathological scoring system, a standardized method that assigns numerical scores to multiple microscopic features, for IgG4-RD.
To do that, they retrospectively analyzed tissue samples from 96 adults who were diagnosed with marked plasma cell infiltration at a hospital in China between 2012 and 2024. Of these, 47 (median age 61; 71.7% men) were diagnosed with IgG4-RD, while the remaining 49 (median age 55; 32.7% men) had other diseases.
The researchers first compared the microscopic features of tissue samples from the two groups to identify those that best distinguished IgG4-RD from other conditions.
Compared with the non-IgG4-RD group, tissue samples from people with IgG4-RD contained significantly more IgG4-producing plasma cells and a much higher proportion of these cells among all plasma cells.
They were also significantly more likely to show the disease’s characteristic swirling pattern of scar-like tissue, inflammation around nerves, inflammation that blocked small veins, and infiltration by eosinophils (a type of immune cell involved in inflammation).
The researchers also found differences in the numbers of tertiary lymphoid structures (organized clusters of immune cells forming in tissues) and nerve bundles (groups of nerve fibers within tissues) between the two groups.
Among the individual microscopic features, the proportion of IgG4-producing plasma cells showed the highest diagnostic accuracy for distinguishing IgG4-RD from other conditions, followed by the total number of these cells and the characteristic swirling pattern of scar-like tissue.
The researchers used statistical modeling to combine all eight microscopic features into a weighted 12-point scoring system, assigning each feature a numerical value based on its relative contribution to the prediction of an IgG4-RD diagnosis.
The optimal diagnostic threshold was a score of 5.5 points or higher, allowing researchers to correctly identify 95.7% of people with IgG4-RD while correctly ruling out all participants without the disease.
Overall, the new scoring system outperformed the 2019 ACR/EULAR classification criteria, internationally recognized standards used to support an IgG4-RD diagnosis, as well as commonly used microscopic diagnostic criteria based on cell counts and tissue features.
To make the scoring system easier to use in routine practice, the researchers developed a simplified version based on four tissue features. Using a cutoff of 4 points, it correctly identified 93.6% of IgG4-RD cases while again correctly ruling out all patients without the disease.
The researchers noted that because the study was conducted at a single medical center and involved a relatively small number of patients, the scoring system should be validated in larger, independent groups of patients.
Still, they said, it offers a “reproducible framework that enhances [IgG4-RD diagnosis] objectivity and consistency between [experts]” and could complement existing diagnostic approaches in routine clinical practice.
Leave a comment
Fill in the required fields to post. Your email address will not be published.