Cory Perugino, DO, rheumatologist and IgG4-RD researcher at Massachusetts General Hospital, breaks down the challenges of diagnosing IgG4-RD and why clinical clues matter just as much as lab tests.
Transcript
Yeah. Diagnostic testing is still a pretty big limitation in the world of IgG4-related diseases for doctors figuring out what’s going on.
We’ve made a lot of strides with a lot of other autoimmune diseases, like rheumatoid arthritis. We have diagnostic tests for lupus. We have diagnostic tests — these are simple blood tests for antibodies that can help confirm a diagnosis.
Most of those are really confirmatory diagnoses after the disease is suspected based on symptoms or physical exam findings. With IgG4-related disease, we do rely a lot on the bloodwork for IgG4 levels, and there’s a lot of limitations to that.
IgG4 in the blood could be elevated for a plethora of other diseases. Really, any chronic inflammatory disease could raise the IgG4 level, so it’s really not specific to IgG4-related disease.
Usually, a biopsy is needed for various reasons to diagnose this disease. One of the main reasons we often rely on or need a biopsy is to rule out or exonerate a differential diagnosis, like cancer or malignancy. So that’s often an important caveat. The biopsy can be helpful to confirm a diagnosis as well.
There are features on a biopsy that are more consistent and more compelling for IgG4-related disease, including the number of IgG4-expressing cells on the biopsy.
There really is not one test, though, that completely confirms or diagnoses this disease, and it really does rely on a physician putting the pieces together, recognizing patterns, and interpreting all of the data simultaneously.
That data could be from radiology, like a CAT scan or MRI; a biopsy, like I was just mentioning with IgG4-expressing cells; bloodwork; as well as a history and physical exam of a patient. So it’s really a full package that’s put together to really diagnose the disease.
