VIDEO: Prevalence of IgG4-related disease still not fully understood

Editor's note: This is an automatically generated transcript. Please notify editor@healio.com if there are concerns regarding accuracy of the transcription.

IgG4-related disease is an immune mediated condition that probably has an autoimmune basis, although we don't know that for sure. The disease was first recognized to be a unique condition in 2003 but clearly, if one looks at the medical literature, one can find patients who had this condition going back at least to the 1800s. IgG4-related disease is a unifying diagnosis for a lot of different conditions that were, up until 2003, considered to be individual diseases.

For example, renal thyroiditis a disease of the thyroid gland, was thought just to be a unique thyroid diagnosis but, in fact, renal thyroiditis is part of IgG4-related disease. The same is true for retroperitoneal fibrosis or Ormand's disease as it was termed when it was described in the 1940s. Retroperitoneal fibrosis is also part of IgG4-related disease. Similarly, Kuttner's tumors, that's K-U-T-T-N-E-R-'S. These are swellings in the submandibular gland that were thought to be a disorder unique to the submandibular glands but, in fact, they're one of the cardinal manifestations of IgG4-related disease. And then finally, it's clearly a multiorgan disease, it's important not to forget to mention the pancreas.

So, autoimmune pancreatitis, which has gone by a number of different names for the past several decades, is, in fact, one of the most important manifestations of IgG4-related disease. So, IgG4-related disease is a multiorgan disease that probably has an autoimmune basis. And we describe it as a fibroinflammatory disorder because one of the cardinal manifestations of the disease is, in fact, fibrosis which occurs in all affected organs almost from the time they are involved with the disease. So how common is it? It is difficult to know for sure right now. The disease got its ICD-10 code only in October of 2023. So, the epidemiology of the disease remains somewhat poorly understood, at least in terms of the overall prevalence. Reasonable estimates, I think, are that there are probably around 40,000 cases in the United States, though I suspect that that number will go up as the ICD-10 code is out for a longer period of time, and more and more physicians are becoming educated about this disease. It's important to remember that the disease was not in medical textbooks and wasn't in medical curricula when most of us were in medical school.

I will say about the epidemiology of the disease, that it is clear, it is more common in men than in women. The classic patient is a middle aged to older male patient. Probably two thirds of the patients are men as opposed to about one third are women. The disease is described in children, though it is less common in children than it is in adults.

One final bit of information about the clinical epidemiology of the disease is that not only is the disease more common in men than in women, there is substantial evidence that it is also more severe in general in men than in women. And by this, I mean it's more likely to cause internal organ involvement, to involve the pancreas, the bile ducts, the kidneys, the lungs, et cetera in male patients than it is in female patients. The precise reason for this is not at all clear. It's one of the many mysteries of this disease that remain.