IgA vasculitis is one of the most common vasculitis in children. The pathogenesis is unclear. Previous studies believe that it is related to IgA, especially IgA1. Antigens and IgA form immune complexes, which are deposited on the walls of small blood vessels, causing vasculitis . The causes of IgA vasculitis are mostly related to infection, vaccination, tumor, and drugs. Previous studies have shown that among the infections associated with IgA vasculitis, respiratory tract infections are the main one, accounting for 42%-53.5%, followed by gastrointestinal tract (2.2%-5%). A study on HSP-related infections in Anhui, China showed that streptococcal infections are the most (17.08%), followed by Helicobacter pylori (5.92%) and Mycoplasma pneumoniae (4.83%), and anti-infective treatment can speed up the remission of patients . Studies have also shown that throat swabs in IgA vasculitis test positive for group A streptococci as high as 75% . We reported the first case with Mycoplasma pneumoniae IgM positive, and she had pharyngeal congestion and tonsil secretions, which may have caused respiratory infections, inducing IgA vasculitis. In the second case, no obvious pathogen was detected, but the white blood cells and CRP were elevated, suggesting that there may be a bacterial infection, which may be related to antibiotics after admission. Gastrointestinal symptoms secondary to gastrointestinal vasculitis, causing blood components to penetrate into the interstices of the intestinal wall, intestinal wall edema and hemorrhage, tissue ischemia, necrosis, and ulcer formation. Intestinal wall edema and thickening cause intestinal obstruction and intussusception. It has been reported that the most commonly affected site is the small intestine, of which the descending duodenum is the most susceptible . The study of Eon Jeong Nam et al stated that the terminal ileum is the most vulnerable, but this is based on adult reports . So far, we reviewed the literatures published by PUBMED, 14 of which are IgA vasculitis with terminal ileitis (not including our 2 cases), of which only 3 literatures reported that 5 children had terminal ileitis [4, 11, 12]. A Chinese study on childhood IgA vasculitis showed that capsule endoscopy revealed that the jejunum was the most affected site, accounting for 96.7%, followed by the descending duodenum (33.3%), and no colon involvement was found . The common manifestations are erosions and ulcers. The cause of terminal ileitis may be because the patch nodules in the terminal ileum are rich in IgA, which causes the deposition of immune complexes . Moreover, the ileocolonic branch of the superior mesenteric artery is the longest branch and is prone to under perfusion . We reported two cases of children with duodenal ulcer and multiple ulcers in the terminal ileum. Duodenal ulcer is not uncommon in the gastrointestinal manifestations of IgA vasculitis, but the first case of giant ulcer in a child has not been reported, and it needs to be differentiated from malignancy. Terminal ileitis is rarely reported in children with IgA vasculitis. It needs to be differentiated from other diseases, especially Crohn. More and more studies have shown that IgA vasculitis may be related to Crohn. There are reports in the literature that Crohn's disease is diagnosed 3 years after the diagnosis of IgA vasculitis . Moreover, IBD patients developed IgA vasculitis after being treated with adalimumab . There are also 2 literature reports that 3 cases of children with Crohn's disease were diagnosed with IgA vasculitis [4,12]. Another study showed that the incidence of IgA nephritis in IBD patients was significantly higher than that in non-IBD patients. Among 83 patients with IBD, renal biopsy from 20 patients showed IgA nephritis . These indicate that there may be a relationship between IgA vasculitis and inflammatory bowel disease. Other differential diagnosis includes infections, such as Yersinia, cytomegalovirus, Salmonella, Mycobacterium tuberculosis, malignant diseases, such as lymphoma, drug-induced vasculitis, common drugs include NSAIDs, contraceptives, and digoxin, Eosinophilic gastroenteritis .
Diagnosis of atypical IgA vasculitis is difficult, especially when gastrointestinal symptoms appear before the rash, IgA vasculitis is easily confused with acute abdomen. There were reports of 2 cases of children with acute abdomen symptoms, and terminal ileitis was found during abdominal exploration. There are also reports of adults with appendicitis-like manifestations undergoing abdominal exploration, and terminal ileitis was detected. These patients all developed rashes on their lower limbs after abdominal exploration, and were therefore diagnosed with IgA vasculitis [6, 11]. Our first case had symptoms similar to appendicitis: tenderness in the right lower abdomen, and abdominal ultrasound and CT showed thickened appendix. Fortunately, our patient did not undergo surgery. Abdominal ultrasound of these two cases showed mesenteric thickening, edema and thickening of the intestinal wall. Atypical IgA vasculitis requires biopsy and histological examination to identify other diseases. The histopathological manifestations of typical IgA vasculitis are leucocytoclastic vasculitis. IgA deposits can be seen on the blood vessel wall, which requires immunohistochemistry. However, not all biopsy specimens can detect vasculitis. Studies have reported that few duodenal specimens can detect IgA deposits , and upper gastrointestinal endoscopy is less sensitive in diagnosing vasculitis. This may be due to the localization of the biopsy to the mucosal layer . Typical cases do not require biopsy, and atypical cases require IgA detection in the skin and gastrointestinal tract when other diseases need to be ruled out. In our first case, the histology of the duodenum found vasodilation and congestion, suggesting the possibility of vasculitis. However, both children had obvious lower extremity rashes later. Although upper gastrointestinal endoscopy and histology cannot directly diagnose IgA vasculitis, it plays an important role in assessing the location and severity of the lesion, including differential diagnosis. Although upper gastrointestinal endoscopy and histology cannot directly diagnose IgA vasculitis, it plays an important role in assessing the location and severity of the lesion, including differential diagnosis, especially when those cases who show duodenitis and terminal ileitis need to be differentiated from other diseases, such as Crohn. In addition to the symptomatic treatment of IgA vasculitis, oral prednisone 1-2 mg/kg/d is recommended, but when serious complications (such as severe brain, lung, gastrointestinal involvement) occur, high-dose methylprednisolone(10-30mg/kg/d) can be used the maximum is 1g/kg, and the dose will be gradually reduced after 3 days . However, it should be noted that steroid therapy may reduce the follicles of the intestinal mucosa, affect mucosal regeneration and healing, and increase the risk of intestinal perforation . Since the renal of the two cases reported in this report were not involved, we did not discuss IgA nephritis involvement did not occur in the two cases reported in this report, we did not discuss IgA nephritis.