A severe case of sclerosing mesenteritis

Abstract

Sclerosing mesenteritis is a rare benign disease presenting with chronic inflammation of the mesenteric adipose tissue and variable degrees of fibrosis. A 47-year-old black man presented to the emergency department with symptoms of small bowel obstruction, requiring surgical treatment. The laparotomy revealed a stenosis of the distal ileum with mesenteric thickening and an enterectomy was performed. The postoperative period was complicated by the maintenance of bowel obstruction. The patient underwent a second laparotomy, in which the fibrosing process of the mesentery was much aggravated, and an ileo-colic resection was needed. After knowledge of the histological diagnosis, the patient was started on immunomodulators with clinical improvement. At 26 months of follow-up, patient is asymptomatic under medical treatment. This is the first report, to our knowledge, of a patient with progressive fibrosis in such short period of time requiring surgical re-intervention for bowel obstruction, owing to sclerosing mesenteritis.

Background

Sclerosing mesenteritis is a rare benign disease, with approximately 200 cases described in the literature, that presents with chronic inflammation of the mesenteric adipose tissue and variable degrees of fibrosis.^{1 2} The reported prevalence of this disease ranges from 0.16% to 3.4%, depending on if the method of diagnosis was radiological or an autopsy.^1–6 It occurs more frequently in men than women (2:1) and is usually diagnosed in the fifth to seventh decade of life.^{1 7} Its aetiology and pathogenesis are still poorly understood and thought to be associated with abdominal trauma, previous surgery, autoimmunity, ischaemic injury, malignancy and infections.^{1 8}

The forms of presentation vary between recurrent abdominal pain, bowel obstruction and abdominal mass, with varying degrees of inflammation and fibrosis.¹

Pathological findings are non-specific, including mesenteric lipodystrophy due to adipocyte necrosis, mesenteric panniculitis secondary to chronic inflammation and finally sclerosing mesenteritis with fibrosis.^{1 7}

Treatment for sclerosing mesenteritis is empirical and justified only in symptomatic patients.⁸ Surgery seems to be indicated only in cases of bowel obstruction.^{7 8} Despite the overall good prognosis, morbidity and chronic debilitating course can happen in 20% of patients.⁹

Case presentation

A 47-year-old black man presented to the emergency department with abdominal pain, bloating, decreased appetite and inability to pass gas or stool, progressing over a week. He denied vomiting. Previous medical history consisted only of appendectomy by laparotomy 30 years earlier. No allergies were known.

Investigations

Physical examination revealed abdominal bloating with diffuse pain to palpation and no rebound tenderness.

Blood tests revealed a slightly elevated C reactive protein (13 mg/dL).

Abdominal X-ray revealed some small bowel gas/fluid levels (figure 1).

Figure 1.

Abdominal X-ray on admission: small bowel distension and air/fluid levels with absence of colonic gas.

Abdominal CT scan revealed severe small bowel distension with no identifiable point of obstruction; pneumoperitoneum was absent (figure 2).

Figure 2.

Abdominal CT scan on admission: marked small bowel distension with no evident point of obstruction. (A) Axial plane and (B) coronal plane.

A nasogastric tube was placed and drained a moderate amount of enteric fluid.

Differential diagnosis

Following the findings of small bowel obstruction, the considered hypotheses were

1. Adhesions due to the previous surgery.

2. Malignancy.

3. Internal hernia.

Treatment

A laparotomy was performed, revealing distention of the small bowel proximal to the distal ileum, where a segment presented a thickened mesentery and bowel wall with narrowing of the lumen (figures 3 and 4). There were no other findings on gross inspection. A segmental enterectomy with primary anastomosis was done. The postoperative period was complicated by prolonged ileus, with abdominal distension and vomiting despite several episodes of diarrhoea daily. The patient was started on a nil per mouth regimen and parenteral nutrition. Since the ileus persisted, a CT abdominal scan was repeated and established small bowel distension without distension of the colon or rectum and densification of mesenteric fat (figure 5).

Figure 3.

Intraoperative image showing the thickened mesentery and bowel wall and narrowed lumen in the distal ileum.

Figure 4.

(A) Small bowel segmental resection specimen and (B) detail of the wall thickness and stenosis.

Figure 5.

CT scan on the 12th postoperative day—small bowel distension with absence of colonic gas. Mesenteric fat densification.

The patient was reoperated on postoperative day 17. The fibrosing process of the mesentery was found to be much aggravated, particularly in the right iliac fossa, once again causing bowel obstruction (figure 6). After extensive adhesyolisis, the fibro-inflammatory process was found to involve not only the anastomosis but also the mesentery of the distal and proximal small bowel over a total length of approximately 70 cm. An ileo-colic resection with primary anastomosis was done to relieve the obstruction.

Figure 6.

(A) Intraoperative image of gross inspection in the second surgery: exuberant fibrotic process in the right iliac fossa. (B) Area of fibrosis in detail.

The histopathological result of the segmental enterectomy revealed a fibro-inflammatory process with β-catenin negative fibroblasts and IgG4 negative immunostaining, consistent with sclerosing mesenteritis.

The patient was started on corticosteroids 4 days after the second surgery (methylprednisolone 1 g/day for 3 days followed by deflazacort 60 mg/day) with rapid clinical improvement. On the fifth day he had bowel movements and on the eighth day he tolerated oral feeding.

The patient was discharged 22 days after the second surgery, on oral deflazacort and azathioprine.

Outcome and follow-up

Over the following 2 months, he was twice readmitted with sub-occlusive bowel syndrome that reverted with conservative treatment. Since then, the patient has been asymptomatic, maintaining a stable weight, and was able to return to work, with a follow-up of 26 months. Patient is regularly reassessed by an autoimmune diseases doctor and by a surgeon. Autoimmunity laboratory tests were positive only for antinuclear antibodies (1/160). IgG levels were normal.

He remains under immunomodulatory therapy with deflazacort and azathioprine.

Discussion

In the literature, sclerosing mesenteritis can also be referred to the terms mesenteric panniculitis, mesenteric lipodystrophy or mesenteric sclerosis. According to Emory et al, ¹ these terms are used to differentiate three stages of the same disease. The first stage is mesenteric lypodistrophy consisting of adipocyte necrosis; the second stage is mesenteric panniculitis with chronic inflammation, lymphocytic infiltrates and lipid necrosis; the third stage consists of sclerosing mesenteritis, identified by the presence of diffuse fibrosis, calcifications and shrinkage of the mesentery.

The aetiology and pathogenesis of sclerosing mesenteritis are still poorly understood and mechanisms thought to be involved are trauma, previous surgery, autoimmunity, ischaemic injury, malignancy and infections.^{1 8} Our patient had had a previous laparotomy for appendectomy.

IgG4-related immunopathological processes might be involved in the pathogenesis,^{8 10 11} but in the case presented there was no IgG4 staining in the specimen nor elevated IgG in the serum.

In a case series⁸ of 92 patients, abdominal pain was the most frequently reported symptom (70%), followed by abdominal bloating and distention (26%), diarrhoea (25%) and weight loss (23%). In that series, 24% of patients presented with small bowel obstruction, while 10% were asymptomatic at the time of diagnosis. Also 35% of patients had a previous history of abdominal surgery.

Diagnosis is challenging to surgeons, radiologists, gastroenterologists and pathologists.

Blood tests are usually normal as was the case with our patient.

There are two CT signs that are considered to be specific for sclerosing mesenteritis. The preservation of the fatty tissue density surrounding the mesenteric vessels and soft tissue lesions is referred to as fat-ring sign, and the identification of a band of soft tissue surrounding the inflamed mass is called tumorous pseudocapsule.¹² None of these signs were identified in our patient’s CT on admission, probably due to the exuberant small bowel distension.

In symptomatic patients, treatment should be tailored according to the severity and type of individual symptoms.¹³ Patients with sclerosing mesenteritis-related complications such as intractable bowel obstruction should undergo surgery, while those with non-obstructive symptoms might benefit from medical therapy.

In Akram’s case series,⁸ treatment included medical therapy alone in 26%, surgery alone in 13%, surgery followed by medical therapy in 9% and 52% received no treatment. Pharmacological agents used for treatment include tamoxifen, prednisone, budesonide, colchicine, azathioprine, methotrexate and thalidomide.^{8 14}

Overall prognosis is usually good and recurrence seems to be rare. However, long-term follow-up is advisable.

In this case, surgery was necessary for establishing the diagnosis and resolving the bowel obstruction. However, the disease course was very aggressive, as the fibrosis progressed, making a second laparotomy necessary. On the second operation, the decision to perform a primary anastomosis instead of a stoma was made as there was no peritoneal contamination, the bowel was well vascularised and it was preferred over an ileostomy with the inherent risk of dehydration and predicted technical difficulty of a future surgery to close the stoma.

The immunomodulatory therapy was discussed with an autoimmune disease specialist, as soon as the histopathological diagnosis was known. There is no consensus on the optimal medical treatment for sclerosing mesenteritis due to small number of known cases. However, most schemes described rely on immunomodulation, most frequently using steroids. As with other inflammatory and autoimmune diseases, steroids are of great benefit in the acute phase and often a first-line option. Given the histopathological diagnosis and the severity of the disease with rapid progression of fibrosis after the first surgery, the risk of progressive fibrosis and obstruction was thought to outweigh the risk of corticotherapy and fistula formation. For those reasons, immunomodulatory therapy was started before resuming oral tolerance using intravenous methylprednisolone. As clinical evolution demonstrated, the immunomodulatory therapy was the key to control the inflammatory process leading to fibrosis and stenosis, contrary to the disease course observed after the first surgery.

To our knowledge, this is the first report of a patient with sclerosing mesenteritis presenting with progressive fibrosis in such a short period of time, requiring surgical re-intervention for bowel obstruction. Symptom remission was achieved with the combination of surgery followed by medical treatment, as was previously reported in the study by Akram et al.⁸

Learning points.

• Sclerosing mesenteritis is a rare disease characterised by mesenteric fibrosis.

• It most frequently presents as abdominal pain, mass or bowel obstruction.

• ‘Fat-ring sign’ and ‘tumorous pseudocapsule’ are specific CT findings, but diagnosis is often incidental during surgery.

• A combination of surgery and immunomodulatory therapy can be required to control symptoms and disease progression.