Sclerosing mesenteritis is a rare chronic fibrosing inflammatory disease of ambiguous pathogenesis primarily diagnosed in late adult life while pediatric cases are very uncommon because children have mesenteric fat than adults [
1‐
3]. It is a benign disorder mainly involving the small-bowel mesentery; however, mesocolon, peripancreatic region, omentum, pelvis or retroperitoneum may be also involved. Both mesenteric panniculitis and mesenteric lipodystrophy are considered to be histological variants of sclerosing mesenteritis [
4]. Viswanathan and Murray reported one case and summarized another 16 pediatric cases from the literature and found that the average age at diagnosis in children was 6.5 years [
2]. In our case, the lesion was extensive and involved small intestine, ascending mesocolon, omentum and peritoneum, leading to intractable bowel obstruction. Clinical symptoms are usually non-specific, including abdominal pain, anorexia, fatigue, weight loss, fever, abdominal mass, ascites, pericardial effusion, diarrhea and constipation [
1‐
3]. Laboratory examinations including C-reactive protein, erythrocyte sedimentation rate, complete blood count, and biochemistry are also non-specific, which renders a diagnostic challenge for clinicians. Abdominal CT or ultrasonography may play an important role in diagnostic evaluation and the most common finding is a soft tissue mass at the root of small bowel mesentery [
5]. In the present case, massive peritoneal cavity effusion resulted in a negative finding on CT scan. A definite diagnosis is dependent on histopathology, which usually reveals fat necrosis, chronic inflammation and fibrosis but can be variable from case to case. These histological variants may reflect the state of a chronic inflammatory process; necrosis in mesenteric fat may represent disease progression and eventually progress to fibrosis which leads to retractile mesenteritis [
6]. In the present case, infiltration of chronic inflammatory cells, fat necrosis and fibrosis were all observed in the histological findings from initial and subsequent surgical specimens, but due to lack of awareness of the disease, a diagnosis of sclerosing mesenteritis was not recognized at the first operation. Therefore, due to the nonspecific signs and symptoms of sclerosing mesenteritis, diagnosis is mainly made through a combination of histopathological and imaging (preferably abdominal CT) findings [
7].
A recently defined subtype, IgG4-related sclerosing mesenteritis, has been reported to be closely related to IgG4-related disease and one such case was reported in children [
8‐
10]. In our case, IgG4 serum subclass levels or tissue immunohistochemistry were not performed.
The optimal therapeutic strategy for sclerosing mesenteritis remains unclear. Some asymptomatic or mild clinical cases may resolve spontaneously without therapy. In some cases with intensive fibrosis leading to intractable bowel obstruction or perforation, surgical resection or ileostomy might be required [
1‐
3]. Medications including corticosteroids, thalidomide, cyclophosphamide, colchicine, azathioprine and tamoxifen have been reported to induce remission of sclerosing mesenteritis [
11‐
13]. Most of the previous reported pediatric cases were successfully treated with corticosteroids. Our patient was started on corticosteroids at 2 mg/kg after definitive diagnosis was made and had a clinical remission in 4 weeks. Due to the severity of intestinal inflammation, we decided to keep him on corticosteroids at 2 mg/kg for another 4 weeks and then slowly weaned off it over 6 months.