Indeterminate Colitis

 

Ulcerative colitis

Crohn’s disease

Localization within gastrointestinal tract

Especially colon and rectum

Whole gastrointestinal tract

Ileum

Not except in backwash ileitis

Often involved

Colon

Left > right

Right > left

Rectum

Commonly involved

Typically spared

Distribution within gastrointestinal tract

Diffuse (continuous)

Segmental (discontinuous)

Ulcers

Superficial ulcers

Aphthous ulcers; confluent, deep, linear ulcers

Pseudopolyps

Common

Uncommon

Skip lesions

Absent

Present

Cobblestone pattern

Absent

Present

Deep fissures

Absent, except in fulminant colitis

Present

Fistulae

Absent, except in fulminant colitis

Present

Mucosal atrophy

Marked

Minimal

Thickness of the wall

Normal

Increased

Fat wrapping

Absent

Present

Strictures

Uncommon

Present


From Ref. [13], reproduced with permission from Elsevier




Table 16.2
Microscopic features used for the diagnosis of inflammatory bowel disease







































































 
Ulcerative colitis

Crohn’s disease

Crypt architectural irregularity

Diffuse (continuous)

Focal (discontinuous)

Chronic inflammation

Diffuse (continuous); decreases proximally

Focal (discontinuous); variable

Patchiness

Uncommon

Common

Localization

Superficial

Transmucosal

Sometimes in submucosa

Transmural

Serositis

Absent, except in fulminant colitis

Present

Lymphoid aggregates

Frequent in mucosa, submucosa

Common, transmural

Granulomas

Absent, except with ruptured cysts

Present

Acute inflammation

Diffuse (continuous)

Focal (discontinuous)

Crypt epithelial polymorphs

Diffuse (continuous)

Diffuse (continuous)

Crypt abscesses

Common

Uncommon

Mucin depletion

Present, pronounced

Uncommon, mild

Neuronal hyperplasia

Rare

Common

Muscular hypertrophy

Absent

Present

Paneth cell metaplasia

Present

Uncommon

Pyloric gland metaplasia

Rare

Present


From Ref. [13], reproduced with permission from Elsevier


These tables illustrate that differentiating between ulcerative colitis and Crohn’s disease is not always easy. It is obvious that few patients will fit exactly into this classification system, and there is no consensus on the number of features needed for one diagnosis or the other. Some pathologists also tend to subdivide indeterminate colitis into that which is more like ulcerative colitis and that which is more like Crohn’s disease [14]. It is also recognized that indeterminate colitis more frequently occurs among children than adults [7, 15].

There has been some expectation that biological markers will aid in differentiating between the two diagnoses. Perinuclear antineutrophil cytoplasmic antibody is a marker for ulcerative colitis but is only present in approximately 60 % of cases and is not considered to be of value in the differential diagnosis. Other biological markers (e.g., anti–Saccaromyces cerevisiae antibody) are no better, and just as with genome studies they are not widely used clinical practice [1618]. However, positive serology preoperatively may identify patients who are likely to develop pouchitis after an ileal pouch–anal anastomosis (IPAA) [19]. Good endoscopy with multiple biopsies from all levels of the colon and rectum, and the opinion of a skilled, dedicated IBD pathologist, is currently the best means of accurate diagnosis. This results in a small percentage of patients with indeterminate colitis; however, most eventually behave as having ulcerative colitis and only a few develop overt Crohn’s disease [20]. A better understanding will determine whether indeterminate colitis is a separate pathological entity or simply a stage in the progression toward one of the classical IBD diagnoses.



16.3 Surgery in a Patients with Indeterminate Colitis


Several large series of restorative pouch surgery indicate that a diagnosis of indeterminate colitis is compatible with successful IPAA [21]. The risk of pouch failure is not substantially increased, but a tendency for more complications has been noted in some studies but not others [22]. A group from the Mayo Clinic initially reported a slightly higher failure rate in patients with indeterminate colitis [23]; however, data from the Cleveland Clinic show no differences with respect to functional outcomes or complication rates [24]. The St. Mark’s Hospital experience is that as long as indeterminate colitis does not have features favoring Crohn’s disease, there are no differences in failure rates or functional outcomes [14]. Today, most surgeons would agree that – notwithstanding a slight uncertainty regarding an increased risk of pouch failure –advising patients with indeterminate colitis to consider having IPAA is justified [25]. In terms of risks for developing pouchitis and cancer, there seem to be no major differences compared with ulcerative colitis [26].

Yet a dilemma remains: operating on patients with IBD unclassified does not automatically infer that the pathologist’s report will conclude a diagnosis of indeterminate colitis. The preoperative diagnosis is based on mucosal biopsies, whereas the colectomy specimen provides full-thickness material, and the diagnosis may turn out to be Crohn’s disease. With this in mind, most surgeons recommend a staged procedure, with a colectomy and end ileostomy as the first step. This has the advantage of giving the pathologist a better basis for a definitive diagnosis. In the case of Crohn’s colitis and a patient wishing for a restorative option, the indication for performing an ileorectal anastomosis is stronger, provided the rectum is reasonably healthy. Other alternatives include proctectomy and ileostomy, a continent ileostomy, and expectant, keeping the rectum under surveillance.

In indeterminate colitis the options of an ileorectal anastomosis or an IPAA must be thoroughly discussed with the patient based on several factors, which must be weighed against each other. The pathologist might be inclined toward one or another diagnosis. The rectum itself must be assessed as early as possible after colectomy; waiting too long often results in a diversion (exclusion) proctitis that can be difficult to distinguish from ongoing IBD. Proctitis of some severity, especially with signs of reduced rectal compliance, makes ileorectal anastomosis a less attractive or even impossible alternative. My practice is to recommend treatment with local rectal 5-aminosalicylic acid after colectomy – at least until a definite decision on a next step has been made. In ulcerative colitis, and hence more so in indeterminate colitis, an ileorectal anastomosis is an alternative to proctectomy and a pelvic pouch in select cases. The most obvious is female patients with a strong wish for childbearing; ileorectal anastomosis avoids pelvic dissection to minimize the risk of adhesions affecting the fallopian tubes [27, 28]. Some male patients also absolutely cannot accept even a minute risk of iatrogenic sexual dysfunction. In the elderly, the reduced overall surgical risk involved in an ileorectal anastomosis and the possible worse functional outcome after IPAA might lead patients to choose the rectum-sparing alternative.

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Oct 30, 2017 | Posted by in ABDOMINAL MEDICINE | Comments Off on Indeterminate Colitis
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