Rare mesenteritis linked to IgG4 treatable without surgery: Study
Glucocorticoids as effective as invasive surgery, researchers say
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IgG4-related sclerosing mesenteritis (IgG4-SM), a rare and often overlooked manifestation of IgG4-related disease (IgG4-RD) treated in many cases by surgery, may respond to less invasive approaches, a study from China found.
IgG4-SM is marked by inflammation and scarring of the mesentery, the tissue that anchors the intestines to the back wall of the abdomen. Data demonstrated that people with the disease were mostly men aged 60 or older, with a greater number of affected organs and higher disease activity than IgG4-RD patients without mesentery involvement.
Because IgG4-SM can appear as tumor-like lesions on imaging scans, many patients undergo surgical removal of mesenteric masses. However, treatment with glucocorticoids — the first-line IgG4-RD treatment — appears to be as effective as surgery in preventing relapses over the long term, the scientists said.
“IgG4-SM is a significant but under-recognized manifestation of IgG4-RD,” the researchers wrote. “Glucocorticoid-based therapy achieved outcomes comparable to surgery, challenging the necessity of invasive interventions.”
The study, “Features of IgG4-related sclerosing mesenteritis: A Chinese cohort study and literature review,” was published in Rheumatology and Immunology Research.
Researchers aim to characterize a hard-to-diagnose condition
IgG4-RD occurs when immune cells, particularly those producing the antibody IgG4, infiltrate tissues, causing inflammation and scarring that can result in swelling and tumor-like masses in one or more organs. Depending on the affected organ, the condition can cause a variety of IgG4-RD symptoms and clinical profiles.
When IgG4-RD affects the mesentery, it is known as IgG4-SM. Because the condition can form mass-like lesions “that mimic malignant tumors,” cause nonspecific symptoms, and lacks “specific biomarkers,” it is often difficult to diagnose, the researchers wrote.
To better characterize IgG4-SM, the team drew on data from 29 IgG4-SM patients within a larger group of 1,409 people with IgG4-RD who participated in an observational study (NCT01670695). All were enrolled between January 2011 and October 2024 at the researchers’ hospital.
IgG4-SM patients represented 2.06% of the total group, underscoring the rarity of the condition, and were compared with 87 IgG4-RD patients whose disease did not involve the mesentery.
People with IgG4-SM were significantly older at diagnosis (median age 63 vs. 56) and were significantly more likely to be men aged 60 or older than those without the disease (41.4% vs. 19.5%).
The IgG4-SM group also showed a significantly greater number of affected organs (median of four vs. three), and significantly higher scores on two validated measures of IgG4-RD activity. This suggested that IgG4-SM may reflect a more widespread and aggressive form of IgG4-RD rather than a condition limited to a single area.
To determine whether their findings reflected broader clinical experience, the team reviewed data from 32 previously published cases of IgG4-SM identified through a systematic review of the literature.
They found that abdominal pain was reported by a significantly higher proportion of patients in earlier cases than by those enrolled at their hospital (68.8% vs. 20.7%). The researchers said the difference likely reflects publication bias, as unusual or severe cases with noticeable symptoms are more likely to be reported.
The findings suggest IgG4-SM may often be clinically silent and often discovered incidentally through imaging tests performed for other reasons.
Patients in the hospital group were also significantly more likely to show involvement of the tear glands, salivary glands, and lymph nodes.
CT scans revealed a spectrum of lesions in the mesentery, ranging from mild, hazy inflammation to solid soft-tissue masses. PET-CT scans showed increased metabolic activity in these areas, suggesting aggressive tumors or active inflammation.
Mesenteric lesions showed hallmark features of IgG4-RD, including dense infiltration of immune cells, increased numbers of IgG4-producing immune cells, and tissue scarring. These findings were consistent with those described in earlier reports of IgG4-SM.
Treatment approaches, however, differed sharply between the two groups.
Most patients in the hospital group were treated with glucocorticoids, either alone or in combination with other immunosuppressive medications, and 6.9% required surgery. By contrast, 59.4% of patients in previous reports underwent surgical removal of mesenteric masses, likely because these were mistaken for tumors.
In most hospital cases, treatment significantly eased symptoms and reduced mesenteric lesion size on imaging, suggesting that IgG4-SM patients often respond well to glucocorticoids. While rates of complete disappearance of visible lesions were higher in previous cases, long-term relapse rates were similar between the hospital and prior cases.
Overall, the findings suggest a generally positive long-term outlook, with all seven patients who were followed for more than five years alive at their last follow-up.
“Our findings show that IgG4-SM presents with [variable] manifestations and can often be managed effectively with glucocorticoid-based therapy,” the researchers wrote. They added that “further research is needed to clarify” the biological processes that cause the disease and optimize “diagnostic and therapeutic strategies for this rare but impactful condition.”
