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Evaluating, Diagnosing, and Managing IgG4-RD in Primary Care

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Released: October 26, 2026

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IgG4-related disease (IgG4-RD) can present with diverse, nonspecific symptoms and multiorgan involvement, making timely recognition and accurate diagnosis challenging. Diagnosing and managing IgG4-RD requires a systematic and multidisciplinary approach to patient care. Learn how IgG4-RD generally presents in primary care, the importance of ruling out key mimicking diseases and assessing multiorgan involvement, as well as making the appropriate referrals to key specialties to help ensure evidence-based treatment is prescribed.

Chuck Vega
Chuck Vega, MD, FAAFP
IgG4 RD in primary care


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I generally encourage my primary care colleagues to not be afraid to step up when delivering comprehensive patient care. We can do more than we might think in terms of confirming a diagnosis, initiating and managing treatment, and stretching ourselves to make us better and more valuable resources in our communities.

However, IgG4-related disease (IgG4-RD) is 1 disease where healthcare professionals (HCPs) in primary care should seek assistance from specialists sooner rather than later. The pathway from disease pathology to clinical manifestation, diagnosis, and treatment is complex. Although we play an important role in recognizing potential IgG4-RD cases and initiating the workup, this is not a disease primary care HCPs should manage on their own.

Recognizing and Identifying IgG4-RD:
A major challenge with identifying and diagnosing IgG4-RD is that it often presents in a slow burn. Unlike conditions like giant cell arteritis or ANCA-associated vasculitis that may present with more acute symptoms, IgG4-RD frequently manifests as chronic, unexplained symptoms with or without organ dysfunction.

In primary care, HCPs should pay particular attention to persistent symptoms that involve the neck or back, any unexplained organ dysfunction, and any unusual mass or physical finding. The salivary glands, hepatobiliary tract, pancreas, and retroperitoneum are among the primary sites affected in patients with IgG4-RD.

Of course, HCPs must rule out other key diseases and conditions, including malignancy, when IgG4-RD is suspected. Infections and other autoimmune disorders also belong on your list of differential diagnoses. But note that IgG4-RD can occur on its own or overlap with another autoimmune disorder, further complicating the diagnostic process.

Because IgG4-RD is rare and its presentation can be subtle, it is not necessarily going to be high on our initially suspected diagnoses. Nevertheless, when patients present to primary care with persistent symptoms or an unexplained finding, I encourage HCPs not to let that go, and appropriate imaging may be the first step toward identifying the underlying problem.

Initiating the Diagnostic Workup:
Imaging is essential when IgG4-RD is suspected. In many cases, CT scanning can help identify fibrotic disease involving 1 or more of the commonly affected organs/anatomical regions.

Once a suspicious lesion is identified, HCPs should check patients’ serum IgG4 levels. I also obtain a complete blood count with differential and an inflammatory marker that includes C-reactive protein and/or erythrocyte sedimentation rate. Although these laboratory investigations provide a good starting point, they are not sufficient to establish an IgG4-RD diagnosis. Furthermore, elevated IgG4 levels alone are not diagnostic of IgG4-RD. So, HCPs must consider patients’ full clinical picture—presentation, radiographic findings, serologic features, and pathology—to confirm the diagnosis.

In many cases, getting a tissue biopsy is also necessary because HCPs need to distinguish IgG4-RD from malignancy and other conditions that may produce similar findings. There are classification criteria available from professional rheumatology associations, but I do not recommend memorizing these. This is not a disease that primary care HCPs will encounter every day, and the diagnostic framework is complicated. Rather, I would refer to the published criteria when IgG4-RD is suspected and work closely with specialists to appropriately evaluate patients.

Addressing Delays in Diagnosis:
Another important reality to recognize in primary care is that we cannot diagnose every patient with IgG4-RD quickly. We do not encounter this disease frequently enough to do so, and its slow presentation means that patients may have symptoms for some time before their diagnosis becomes apparent. Then there are more common diseases like malignancy and infection that appropriately take priority in patients’ initial evaluations.

In addition, imaging can identify incidental abnormalities that may never cause harm. Therefore, primary care HCPs must distinguish these findings from clinically meaningful disease without pursuing unnecessary investigations.

I think the best we can do to mitigate diagnostic delays is to provide greater awareness of and appropriate referrals for IgG4-RD. This is why education about IgG4-RD matters. Although primary care HCPs may not see many cases throughout their career, we must recognize the possibility of this disease when patients have persistent and unexplained symptoms, organ dysfunction, or an unusual mass.

Coordinating IgG4-RD Care With Specialists:
As previously mentioned, IgG4-RD is a condition that calls for a team-based approach early in the diagnostic process. But the appropriate referrals will depend on the exact organs involved. For example, if patients have salivary gland lesions or a lacrimal gland mass, I might refer them to otolaryngology or ophthalmology. If retroperitoneal fibrosis is contributing to kidney dysfunction, I would consider involving both nephrology and urology. For those with gastrointestinal or hepatobiliary involvement, gastroenterology and hepatology are important partners to include on the care team. Finally, depending on the location of a lesion or mass, a general surgeon or interventional radiologist may also be needed to obtain a biopsy.

Although I generally do not recommend broad imaging without a clear indication, IgG4-RD may warrant a different approach, especially since this disease is frequently associated with multiorgan involvement. If HCPs identify IgG4-RD in both the neck and retroperitoneum, it may be appropriate to evaluate for additional organ involvement elsewhere in the body.

The goal here is to understand the extent of the disease and bring the right specialists into patients' care as early as possible.

IgG4-RD Treatment Landscape:
The good news is that we now have targeted treatment options for IgG4-RD, and additional therapies are emerging.

Glucocorticoid therapy has traditionally been the first-line IgG4-RD treatment, and it continues to be an effective treatment option either alone or in combination with targeted therapy. Rituximab was the first B-cell–depleting therapy to show efficacy in select patients with IgG4-RD, but it does not currently carry an indication for this disease.

More encouraging developments are being made with newer biologic therapies. The first is inebilizumab, an anti-CD19 monoclonal antibody. It has demonstrated efficacy and safety, including in combination with glucocorticoid therapy, and it is now FDA approved to treat adults with IgG4-RD. Obexelimab is another anti-CD19 monoclonal antibody, but it remains investigational in this space.

These emerging therapies offer hope for improving disease management. In addition, they are bringing greater attention to a condition that often goes unrecognized. That said, as a primary care HCP, I would want a specialist, typically a rheumatologist or immunologist, to help guide treatment for patients with IgG4-RD. This is because glucocorticoids are associated with well-known toxicities, and many patients with IgG4-RD are older adults who may have several comorbidities and face an increased risk of infection.

I do not recommend initiating glucocorticoid therapy independently in primary care for suspected IgG4-RD. Rather, I would feel much more comfortable having a specialist direct that treatment, particularly given the diagnostic complexity and need to balance treatment efficacy with safety.

My take-home message to primary care is this: always remain curious and persistent. When something does not fit, do not dismiss it. Investigate appropriately, consider IgG4-RD when the clinical picture suggests it, and involve specialty care early.

Although we may not be the HCPs who ultimately establish an IgG4-RD diagnosis or direct its treatment, we play an essential role in helping patients reach the right diagnosis and receive the appropriate care.

Your Thoughts:
How often do you consider IgG4-RD in your list of differential diagnoses? You can get involved in the conversation by answering the poll question and posting a comment below.

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