Diagnosis
Talley et al. suggested 3 diagnostic criteria which are still widely used:

the presence of gastrointestinal symptoms,
histological demonstration of eosinophilic infiltration in one or more areas of the gastrointestinal tract or presence of high eosinophil count in ascitic fluid (latter usually indicates subserosal variety),
no evidence of parasitic or extraintestinal disease.Hypereosinophilia, the hallmark of allergic response, may be absent in up to 20% of patients, but hypoalbuminaemia and other abnormalities suggestive of malabsorption may be present. CT scans may show nodular and irregular thickening of the folds in the distal stomach and proximal small bowel, but these findings can also be present in other conditions like Crohns disease and lymphoma.The endoscopic appearance in eosinophilic gastroenteritis is nonspecific; it includes erythematous, friable, nodular, and occasional ulcerative changes. Sometimes diffuse inflammation results in complete loss of villi, involvement of multiple layers, submucosal oedema and fibrosis.Definitive diagnosis involves histological evidence of eosinophilic infiltration in biopsy slides. Microscopy reveals >20 eosinophils per high power field. Infiltration is often patchy, can be missed and laparoscopic full thickness biopsy may be required. Radio isotope scan using technetium (99mTc) exametazime-labeled leukocyte SPECT may be useful in assessing the extent of disease and response to treatment but has little value in diagnosis, as the scan does not help differentiating EG from other causes of inflammation.When eosinophilic gastroenteritis is observed in association with eosinophilic infiltration of other organ systems, the diagnosis of idiopathic hypereosinophilic syndrome should be considered. Management
Corticosteroids are the mainstay of therapy with a 90% response rate in some studies.
Factitious disorder imposed on self, also known as Munchausen syndrome, is a factitious disorder in which those affected feign or induce disease, illness, injury, abuse, or psychological trauma to draw attention, sympathy, or reassurance to themselves. Munchausen syndrome fits within the subclass of factitious disorder with predominantly physical signs and symptoms, but patients also have a history of recurrent hospitalization, travelling, and dramatic, extremely improbable tales of their past experiences. The condition derives its name from the fictional character Baron Munchausen. Factitious disorder imposed on self is related to factitious disorder imposed on another, which refers to the abuse of another person, typically a child, in order to seek attention or sympathy for the abuser. This drive to create symptoms for the victim can result in unnecessary and costly diagnostic or corrective procedures. Signs and symptoms
In factitious disorder imposed on self, the affected person exaggerates or creates symptoms of illnesses in themselves to gain examination, treatment, attention, sympathy or comfort from medical personnel. It often involves elements of victim playing and attention seeking. In some extreme cases, people with Munchausen syndrome are highly knowledgeable about the practice of medicine and are able to produce symptoms that result in lengthy and costly medical analysis, prolonged hospital stays, and unnecessary operations. The role of patient is a familiar and comforting one, and it fills a psychological need in people with this syndrome. This disorder is distinct from hypochondriasis and other somatoform disorders in that those with the latter do not intentionally produce their somatic symptoms.