Sclerosing mesenteritis: A real manifestation or histological mimic of IgG4-related disease?

Fibrotic phenotype of IgG4-related disease

A prompt response to glucocorticoids is a clinical hallmark of IgG4-related disease. However, manifestations characterised by prominent tissue fibrosis on histological examination can be less responsive to glucocorticoid therapy than other types of IgG4-related disease. These manifestations include retroperitoneal fibrosis, fibrosing mediastinitis, Riedel thyroiditis, orbital pseudotumor, and hypertrophic pachymeningitis, among others. To explain this discrepancy, a preliminary distinction into proliferative and fibrotic phenotypes of IgG4-related disease has been proposed on the basis of clinical presentation, pathological features, and response to immunosuppressive therapy. Implications of this classification for patient management remain an important area of investigation. In this Series paper, we aim to dissect the pathophysiology of tissue fibrosis in IgG4-related disease and discuss how clinicians should approach the management of fibrotic manifestations of IgG4-related disease based on the most recent diagnostic and therapeutic developments.

Imaging manifestations of IgG4-related disease

IgG4-related disease is a multisystem immune-mediated disorder associated with lesions manifesting an IgG4-rich plasma cell infiltrate and often raised serum IgG4 concentrations. The disease can mimic neoplastic, infective, and inflammatory processes due to features such as development of masses or organ enlargement. Prompt consideration of this diagnosis is essential to avoid unnecessary investigations and offer appropriate treatments, which can include steroids and other immunosuppressive agents. Although histology is typically diagnostic, imaging is critical to assess disease burden, determine biopsy targets, and evaluate response to treatment. Characteristic imaging features can also point towards the diagnosis in the absence of biopsy. This review highlights these features, as well as more atypical findings, grouped by organ or system. Differential diagnoses are emphasised. The full spectrum of imaging methods is discussed. Whole-body imaging with integrated 2-[18F]-fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography (PET)/computed tomography (CT) has an evolving role in the detection of multi-organ involvement and subsequent follow-up.

Goiter and Abdominal Mass: A Rare Presentation of Riedel's Thyroiditis

Riedel's thyroiditis (RT) is a rare inflammatory autoimmune disease, often associated with various forms of systemic fibrosis such as sclerosing mesenteritis (SM). A woman in her late 30s presented with a diffusely enlarged firm goiter and a mesenteric mass complicated by biliary obstruction and hydronephrosis. Labs and thyroid ultrasound were consistent with autoimmune thyroiditis. Abdominal imaging demonstrated a mesenteric mass that encased mesenteric vessels and ureter. Flow cytometry and infectious workup were negative. Both thyroid and mesenteric biopsies revealed dense fibrosis with patchy lymphoplasmacytic aggregates, no evidence of carcinoma, lymphoma, or IgG4-related disease, which confirmed diagnoses of RT and SM. She improved clinically with steroids. The coincidental timing of thyroid enlargement and the mesenteric mass, and the similarity in histology suggest an association between RT and SM. Overall, the case highlights the challenges in diagnosing RT given its rarity and emphasises the importance of early treatment to prevent systemic involvement.

Anatomic and Functional Imaging of Immunoglobulin G4-related Disease and Its Mimics

Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is an immune-mediated fibrosclerosing disease with tumefactive lesions infiltrated by IgG4-positive plasma cells. Initially described as autoimmune pancreatitis, IgG4-RD is now recognized as a discrete entity and is found to affect virtually any organ in the body. Common extrapancreatic sites include the biliary tree, salivary glands, periorbital tissue, lungs, kidneys, lymph nodes, aorta, retroperitoneum, and thyroid gland. Diagnosis-which relies on histopathologic, serologic, and radiologic features-can be challenging with the disease underdiagnosed, as IgG4-RD often mimics malignancy, infectious processes, or other immune-mediated conditions. Patients may present with signs of compression of nearby structures due to mass effect or with organ failure when the disease is left untreated. The clinical course is complex, with single- or multiorgan involvement and metachronous or synchronous occurrence of lesions. IgG4-RD responds well to glucocorticoid therapy, disease-modifying antirheumatic drugs, and B-cell-depleting biologic agents; prompt diagnosis is important to avoid delay in treatment and unnecessary pharmacologic or surgical intervention. While imaging features may not be specific for IgG4-RD, functional whole-body imaging with fluorine 18-fluorodeoxyglucose PET/CT is a useful adjunct for localizing extrapancreatic sites for biopsy, monitoring therapeutic response, and demonstrating disease relapse. The authors describe the pancreatic and extrapancreatic sites of involvement in IgG4-RD, with imaging features and patterns to aid in distinguishing IgG4-RD from its mimics through a multimodality approach with emphasis on functional imaging evaluation. ^©RSNA, 2023 Quiz questions in the supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article.

Mesenteric Panniculitis, Sclerosing Mesenteritis and Mesenteric Lipodystrophy: Descriptive Review of a Rare Condition

Mesenteric panniculitis (MP) is the preferred nomenclature for a continuum of inflammatory diseases of the mesentery. The diagnosis of MP is often based on the appearance of a mass-like structure at the root of the mesentery. Characteristic histology includes focal fat necrosis, chronic inflammation, and sometimes mesenteric fibrosis. At present, robust literature related to diagnosis and management of MP are limited. MP is postulated to be an immune-mediated chronic inflammatory and/or a paraneoplastic disease. A personal or family history of other autoimmune diseases is commonly apparent. Several inciting events have been identified that possibly act as triggers in the development of the disease. Trauma, abdominal surgery, infection, and various cancers have been associated with mesenteric panniculitis. There are several diagnostic and histologic criteria that aid in making the diagnosis of MP. The differential diagnosis for a mesenteric mass includes neoplastic disease, and a biopsy may be indicated to rule out other conditions. While cases of MP with a short duration of symptoms, or spontaneously regression may occur, some patients experience prolonged periods of pain, fever, and alterations in bowel habit, causing significant morbidity. A variety of medical therapies have been suggested for MP. Only two, thalidomide and low-dose naltrexone, have been prospectively evaluated. For patients with chronic MP, good responses to prolonged corticosteroid treatment have been reported. Novel therapies include thalidomide and low-dose naltrexone. Hormonal and immunomodulatory therapies are also used based on small case series, but these treatments may have significant side effects. Surgical intervention is not curative and is avoided except for relief of focal bowel obstruction secondary to fibrotic forms of the disease.

A rare case report of immunoglobulin G4-related sclerosing mesenteritis and review of the literature

INTRODUCTION

Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is a rare autoimmune disorder involving 1 or multiple organs, most commonly the pancreas, lacrimal glands, and salivary glands. However, IgG4-related sclerosing mesenteritis (SM) involving the small-bowel mesentery is rare. Given that IgG4-related SM usually mimics the imaging characteristics of mesenteric malignancies, its preoperative diagnosis remains challenging. In addition, no specific consensus has been reached regarding the treatment of IgG4-related SM. Therefore, a better understanding of the characteristics, treatment, and prognosis of IgG-related SM is urgently needed. Herein, we report a rare case of IgG-related SM.

PATIENT CONCERNS

A 67-year-old man was admitted to our hospital after incidental detection of an abdominal mass on ultrasound imaging, although he reported being generally well. The findings on triple-phase abdominal computed tomography were highly consistent with a malignant mesenteric tumor.

DIAGNOSES

The hallmark histopathological features along with elevated levels of IgG4 (145 mg/dL) and imaging findings were indicative of IgG-related SM.

INTERVENTIONS

The patient was treated surgically. Postoperative histopathological examinations exhibited tissue infiltration with lymphocytes and IgG4-positive plasma cells, as well as fibrosis.

OUTCOMES

Ten days after surgery, the patient was discharged from the hospital, and did not show any clinical sign of IgG-related SM within 1-year follow-up.

CONCLUSION

This case highlights the mesentery as an uncommon site of involvement as well as how early IgG-related SM can be completely asymptomatic. Thus, this study has advanced our knowledge of IgG-related SM and may improve treatments for similar conditions.

Sclerosing Mesenteritis Mimicking IgG4-related Disease

A 72-year-old man was followed as an outpatient at our hospital for 6 years after surgery for small cell carcinoma of left adrenal gland origin. Follow-up abdominal computed tomography showed a 6-cm mass in the left lower mesentery. The patient underwent open laparotomy. The histological diagnosis was sclerosing mesenteritis. The previous specimens of the left adrenal mass were then re-examined with a microscope, and panniculitis was found around the small cell carcinoma. Both lesions were histologically similar to IgG4-related disease (RD), but they did not completely meet the diagnostic criteria of IgG4-RD clinically or histologically.

A Case of Ileocecal IgG4-Related Sclerosing Mesenteritis Diagnosed by Endoscopic Ultrasound-Guided Fine Needle Aspiration using Forward-Viewing Linear Echoendoscope

A 25-year-old woman had undergone removal of a cryptogenic tumor in the left maxillary sinus 1 year prior to presentation. The patient experienced abdominal pain for 4 days with repeated vomiting episodes; therefore, she was transferred to our hospital by an ambulance. Contrast-enhanced computed tomography revealed a 3-cm tumor in the ileocecal region, which caused small bowel obstruction. Contrast imaging of the ileus tube showed extrinsic compression of the ileocecal region. Forward-viewing linear echoendoscope revealed an irregular hypoechoic tumor measuring 3 cm outside the gastrointestinal tract. Using a 25G needle, endoscopic ultrasound-guided fine needle aspiration (EUS–FNA) was performed. Pathological finding was an inflammatory fibrous tissue with diffuse lymphoplasmacytic infiltration, with more than 10 IgG4-positive cells detected in a high-power field. Re-examination of a pathology specimen of the maxillary sinus tumor provided by the previous attending physician revealed that the inflammatory tissue had diffuse lymphoplasmacytic infiltration, which were accompanied by storiform fibrosis and obliterative phlebitis. Immunostaining revealed more than 50 IgG4-positive cells in a high-power field, a finding suggestive of IgG4-related disease. The serum IgG4 level was 21 mg/dl, which was within the normal range. Treatment was initiated with prednisolone at a dose of 50 mg/day, and the dose was later tapered off. CT and MRI performed 2 months later showed complete disappearance of the ileocecal tumor. The final diagnosis was asynchronously occurring IgG4-related maxillary sinusitis and sclerosing mesenteritis.

[Misty mesentery : Mesenteric panniculitis and associated processes]

BACKGROUND

Sclerosing mesenteritis (SM) and mesenteric panniculitis are rare processes of the mesentery which pose a major clinical and imaging challenge. This review article attempts to introduce a systematic nomenclature to address typical symptoms, imaging and major differential diagnoses.

RESULTS

SM with its subtypes-mesenteric lipodystrophy, panniculitis and retractile mesenteritis-is a chronic process with a very diverse and heterogeneous clinical appearance. The typical radiological characteristics ("misty mesentery", increased lymph nodes, pseudocapsule and "fat halo") are also not very specific. A link between SM and malignant diseases is not proven, but there is controversial discussion. Therefore, if there are doubts about the diagnosis, further examinations and a biopsy are desired.

CONCLUSION

When diagnosing SM, "red flags", i. e. characteristics that are atypical for SM in imaging, should be considered. In case of ambiguous imaging, differential diagnostics should also consider malignant diseases and exclude them.

Sclerosing Mesenteritis

Sclerosing mesenteritis is a rare non-neoplastic disorder characterized by fat necrosis, chronic inflammation, and fibrosis typically of the small bowel mesentery. Our understanding of this disorder is limited by its rarity as well as inconsistent terminology used across the literature. While prior abdominal surgery or trauma, autoimmunity, infection, ischemia, and malignancy have been suggested to be involved in the pathogenesis of the disorder, it remains poorly understood. The clinical course of sclerosing mesenteritis is generally benign with a large proportion of patients diagnosed incidentally on imaging obtained for other indications. In a subset of patients, symptoms may arise from a mass effect on the bowel, lymphatics, or vasculature resulting in bowel obstruction, chylous ascites, or mesenteric ischemia. Symptomatic patients should be treated with a combination of corticosteroid and tamoxifen as first-line therapy based on retrospective case series and experience in other fibrosing disorders. Surgical intervention may be required in those with persistent obstruction despite conservative treatment, though complete resection of the mass is often not feasible given intimate involvement with the mesenteric vasculature. A careful use of terminology and communication between the radiologist, pathologist, and clinicians in the care of these patients will be essential to future efforts at understanding this disease.

[Immunoglobulin G4 Unrelated Idiopathic Mesenteric Sclerosis]

Sclerosing mesenteritis is a rare benign disease with a prevalence of 0.16-3.4% and is characterized by chronic nonspecific inflammation and extensive fibrosis in the adipose tissue of the mesentery although the exact pathogenesis is still elusive. A 65-year-old woman was referred with suspicion of an abdominal mass and biliary stones on abdominal ultrasonography and CT. Bile duct stones were confirmed by endoscopic ultrasonography and successfully treated by endoscopic retrograde cholangiography with stone removal. Furthermore, a 4.7 cm conglomerated mass on small intestinal mesentery was suspected as sclerosing mesenteritis based on the features on abdominal MRI. However, because it could not be differentiated from malignancy without histologic examination, laparoscopic excisional biopsy was performed; it showed only inflammatory cells with extensive fibrosis. Therefore, the abdominal mass was confirmed as sclerosing fibrosis and the patient was followed-up without any treatments because no mass-related symptoms accompanied the findings. Six months later, abdominal CT showed no significant change in the mass. Herein, we report a rare case of incidentally found idiopathic sclerosing mesenteritis.

IgG4-related sclerosing mesenteritis, a rare condition that causes abdominal pain

The identification of IgG4-related disease as a distinct immune-mediated condition encompassing disorders that were traditionally seen as idiopathic has been a revolution in the diagnostic and therapeutic algorithm in several medical fields. This condition usually involves multiple organs (isolated organ involvement is uncommon except in the pancreas) with characteristic histopathological findings. We report a case that was assessed due to abdominal pain and subsequently diagnosed with IgG4-related sclerosing mesenteritis. A comprehensive work-up of the case ruled out other conditions and a diagnosis of IgG4-related sclerosing mesenteritis was made according to radiographic and histopathological criteria.

An Autopsy Case of Mesenteric Panniculitis with Massive Pleural Effusions

BACKGROUND Mesenteric panniculitis (MP) is an idiopathic chronic inflammatory condition of the mesentery. The main symptoms include abdominal pain, abdominal distention, weight loss, fever, nausea, and vomiting. The patients also present with chylous ascites in 14% of the cases and chylous pleural effusion (CPE) in very rare occasions. Despite the previous view of excellent prognosis of MP, two recent papers reported several fatal cases. However, there are still only a few autopsy case reports that describe the macroscopic and histological details of MP cases. CASE REPORT The patient was an 81-year-old Japanese woman. She complained of edema of her lower legs and face, general fatigue, and dyspnea. She was overweight and had type 2 diabetes (T2D). Computerized tomography (CT) demonstrated massive bilateral pleural effusions, with mild pericardial effusion and mild ascites. There was no pulmonary, cardiac or hepatic condition to explain the effusions. However, MP was suspected based on her CT. She gradually deteriorated into respiratory failure. The autopsy revealed CPEs (left 1,300 mL, right 1,400 mL) and MP in the mesentery of the small intestine. Neither neoplasia nor inflammatory conditions other than MP were detected. CONCLUSIONS In rare occasions, patients with MP present with CPE or chylothorax. We thought that a possible mechanism of the CPEs was a diaphragmatic defect. We suspected that being overweight and T2D had an etiological relationship with MP in our patient's case. Adipose tissue of the mesentery is the main focus of MP. We believed that MP would be the best umbrella term of the many synonyms.

[Diseases of connective tissue in IgG4-associated autoimmune diseases]

The IgG4-associated diseases of connective tissue are caused by allergen-mediated autoimmune processes. The retroperitoneum, mesentery and mediastinum as well as other less common localizations, such as the neck, orbit and periarticular connective tissue can be affected. Inflammatory fibrosis is initially dominated by a lymphocytic and plasma cell-rich infiltrate and later by cell-poor storiform fibrosis. Stenosis and occlusion of vessels, ureters and intestines can cause severe complications. Computed tomography (CT) and magnetic resonance imaging (MRI) can be implemented in the diagnostic algorithm to narrow the differential diagnosis, delineate the distribution of fibrosis and reveal complications.

Sclerosing mesenteritis in a 5-year-old Chinese boy: a case report

Background

Sclerosing mesenteritis is a rare fibroinflammatory disorder of unknown etiology that primarily affects the mesentery of the small intestine during late adult life. Only about twenty pediatric cases have been reported to date, but none has been reported in Chinese children.

Case presentation

A 5-year-old Chinese male presented with a 4-week history of recurrent bloating, abdominal pain, anorexia and vomiting. On admission, physical examination showed a severely distended abdomen. Biochemical investigations showed a slightly increased C-reactive protein, and normal serum levels of electrolytes and erythrocyte sedimentation rate. An abdominal film showed small intestine obstruction and massive ascites. An exploratory laparotomy revealed widespread inflammatory fibrotic adhesions between the bowel and the abdominal wall, thickening of the small bowel and massive ascites. During a prolonged hospital course, a 2nd surgery (4 months after 1st exploratory laparotomy) was performed in order to close the ileostomy and revealed that the bowel was still severely edematous, with very tight adhesions between the bowel and the abdominal wall. Histopathological examination of excised mesentery and nodules showed chronic inflammatory cell infiltration, fat necrosis and fibrosis. A diagnosis of sclerosing mesenteritis was finally established. Prednisolone at 2 mg/kg was started and he experienced rapid clinical improvement in 4 weeks.

Conclusions

Sclerosing mesenteritis is extremely rare in children and often misdiagnosed due to its nonspecific clinical manifestation. It is important to be aware of sclerosing mesenteritis when evaluating a child with intractable abdominal pain, bloating, intestinal obstruction and massive ascites.

Surgical management of isolated mesenteric autoimmune disease: addressing the spectrum of IgG4-related disease and sclerosing mesenteritis

IgG₄-related disease (IgG₄-RD) is a rare form of autoimmune sclerosing disease, characterised by elevated serum IgG₄ and tissue IgG₄ levels, specific histopathological findings, multiorgan involvement and adequate response to glucocorticoid treatment. The low incidence and the heterogeneous nature of the disease has made consensus on diagnostic criteria for IgG₄-RD difficult. Whether sclerosing mesenteritis (SM) is considered a manifestation of IgG₄-RD is strongly debated. We present the case of a patient with a history of rheumatoid arthritis who presented with a calcified abdominal mass. She was found to have an isolated, pedunculated mesenteric mass positive for IgG₄ and concurrently elevated serum IgG₄ levels. Clinical features did not classify her disease as either SM or IgG₄-RD as currently described in consensus statements. Concurrent diagnoses of IgG₄-RD, SM and other autoimmune disorders, as well as postoperative recommendations for resected isolated IgG₄-positive masses, are discussed.

Serosal involvement in IgG4-related disease: report of two cases and review of the literature

IgG4-related disease (IgG4-RD) is a recently described entity characterized by lymphoplasmacytic infiltrates, usually mimicking tumors, affecting almost every organ or system. Nevertheless, serosal involvement has been rarely reported. In this article, we report two cases of IgG4-RD with serosal involvement and review the literature. Because of the varied clinical pictures found in our review, we suggest a new terminology for the description of IgG4-RD with serosal involvement.