Co-existance of inflammation of the ileum (ileitis) and diverticular disease in your case, raises some interesting possibilities.
a) Involvement of the distal ileum seen in some cases of ulcerative colitis (UC) is termed "backwash ileitis" (BWI).
It can occur
- as a contiguous lesion in UC involving the proximal colon,
- it can occur in the context of pancolitis, or
- sometimes even seen as a non-contiguous feature.
It generally is accepted as a distinct pathologic process in patients with UC. Basically,it is a mucosa-based inflammatory process, unlike crohn's disease, which is transmural.
b) Both inflammatory bowel disease(IBD) and diverticular disease affect elderly western populations(>60y). Thus there is a liklyhood that they may co-exist. Some reports suggest that Crohn's disease of sigmoid colon may induce diverticulosis.
Also, it may preferentially involve sigmoid colon affected by diverticular disease.
c) "Diverticular-associated inflammatory bowel disease-like colitis"
significantly overlaps clinically with primary inflammatory bowel disease. However, the clinical and the pathologic features of diverticular-associated colitis suggest that it is a distinct clinical entity. Diverticular-associated colitis is a distinct entity that presents with segmental colitis and a variety of clinical, endoscopic, and pathologic features. Diverticular-associated colitis should be considered in the presence of recurrent symptoms after resection for diverticulitis".
d) Yersinial terminal ileitis
: caused by gram negative coccobacilli Yersinia enterocolitica and Yersinia pseudotuberculosis. Mode of spread unclear. Can be due to close contact with animals, or food-borne transmission(dairy products, meat, shell fish).
Common in children but may occur in adolesents or young adults. Causes mesenteric adenitis and terminal ileitis.HLA-B27 phenotypes may be associated with sacroilitis, polyarthritis,or Reiter's syndrome, .Common symptoms
: are fever, diarrhea, and abdominal pain.Diagnosis
: by stool culture.Serologic tests
: useful in diagnosing for past infections.Prognosis
: Mostly self-limiting.Treatment
: appears to be sensitive to amonoglycosides, third generation cephalosporins, chloramphenicol, co-trimoxazole and ciprofloxacin.
Only a full work up may help clarify the reason for the ileitis in your case.