Ulcerative colitis: patterns of involvement in colorectal biopsies and changes with time.Am J Surg Pathol. 1998 Aug;22(8):983-9.

Chronic inflammation, both endoscopic and histologic, in a contiguous and symmetric distribution is said to be important in distinguishing ulcerative colitis (UC) from Crohn's disease. Little is known whether this rule holds during the course of the disease and whether endoscopic/histologic correlation persists. In this study, we analyzed histologic patterns of UC in sequential sets of biopsy specimens to assess whether endoscopic and histologic findings correlate with time and treatment and to see whether distribution changes. Two hundred seventeen sets of colorectal biopsy specimens from 797 sites from 41 patients with clinical UC were studied and correlated with endoscopic findings. Each biopsy specimen was classified as definite or suspicious for chronic colitis or normal. Two histologic patterns of disease were identified: (1) diffuse, when all areas in all pieces from a biopsy segment had clear-cut colitis and (2) nondiffuse, when not all pieces were involved or single pieces had disease and normal mucosa both. Of 41 patients, the maximal extent of histologic disease was pancolitis in 30; 25 had less extensive disease at some point in the course. The maximal extent was left-sided in eight patients, seven of whom had less extent at some point. Of the three patients in whom the maximal extent was proctosigmoiditis, in one the inflammation disappeared. Seventy percent of the biopsy sites had diffuse patterns and 30% had nondiffuse. Histologic and endoscopic disease reverted to normal in 22 and 24 of 41 patients, respectively. Endoscopic and histologic findings were similar in 65% of the biopsy sites. Our results indicate that in long-standing UC (1) histologic disease may revert to normal mucosa, (2) because endoscopy alone may be insufficient to identify the mucosa as normal, biopsies should also be performed on the endoscopically normal mucosa, (3) the full extent of UC often is not established by a single set of biopsies, and (4) nondiffuse chronic inflammation and rectal sparing occurs in UC and are not necessarily markers of Crohn's disease.

Endoscopic and histological patchiness in treated ulcerative colitis. Am J Gastroenterol. 1999 Nov;94(11):3258-62.

OBJECTIVE: Traditionally, contiguous distribution of inflammation (endoscopic and histological) with rectal involvement is thought to be important in distinguishing ulcerative colitis (UC) from Crohn's disease of the colon. Little long-term data are available that prove whether this rule holds during the course of disease as it is modified by time and treatment. The aim of this study was to investigate the prevalence of endoscopic and histological patchiness and rectal sparing in treated UC over time and to correlate these findings with treatment at the time of endoscopy. METHODS: Patients with well-established UC who underwent sequential colonoscopy or flexible sigmoidoscopy with biopsies were included in this study. Patients' medical records including endoscopy/biopsy reports and clinical status/symptoms/treatment at the time of endoscopy were reviewed retrospectively. RESULTS: A total of 32 patients (14 men, 18 women; median age, 45 yr; median UC duration, 15 yr) underwent 175 sequential endoscopies with biopsies (161 colonoscopies, 14 sigmoidoscopies; median, five endoscopies per patient; range, 3-10). Endoscopic and/or histological patchiness was present in 20 of 175 (11%) sequential endoscopies with biopsies over time from 12 of 32 (38%) patients. Endoscopic and/or histological rectal sparing was present in 27 of 175 (15%) of sequential endoscopies with biopsies over time from 14 of 32 (44%) patients. Seven patients had both patchiness and rectal sparing. Therefore, in 47 (27%) follow-up endoscopies in 19 (59%) patients, there was either patchy disease, rectal sparing, or both sometime during the course of disease with treatment. There was no significant difference in treatment, including steroid use and rectal therapy, between those with patchiness and/or rectal sparing and those without. CONCLUSIONS: Contrary to traditional teaching, endoscopic and histological patchiness of inflammation and rectal sparing are common during the course of disease in treated UC and seem to be unrelated to specific therapy.

Atypical rectosigmoid histology in children with newly diagnosed ulcerative colitis.Am J Gastroenterol. 1993 Dec;88(12):2034-7.

BACKGROUND: In the untreated patient with inflammatory colitis, rectal sparing or patchy rectal inflammation is generally considered a sign of Crohn's disease (CD), rather than ulcerative colitis (UC). METHODS: The initial endoscopic rectosigmoid mucosal biopsies obtained at disease onset from 12 untreated children with UC who ultimately required surgery were blindly reviewed (randomly mixed with another 62 specimens obtained from children with CD or treated UC). Biopsies were classified as typical UC if there was diffuse, active inflammation and severe crypt destruction or distortion. Those with patchy, active inflammation and only mild crypt changes were classified as CD. Because all 12 subjects had ultimately been proven to have UC by examination of a subtotal colectomy specimen, for the purposes of this report biopsies read as either normal or CD were both considered evidence of atypical UC with rectal sparing. RESULTS: Five of 12 subjects (seven biopsies) had atypical histology. Mild, patchy inflammation was seen in six rectal or sigmoid biopsies, whereas one rectal biopsy was normal. The remaining seven subjects (10 biopsies) had diffuse inflammation. Two of five subjects with atypical biopsies had an endoscopically normal rectosigmoid, one had patchy inflammation, and the remaining two had diffuse endoscopic changes. All seven subjects with typical UC histology had diffuse endoscopic changes. Subjects with atypical findings could not be differentiated by age, duration, or types of symptoms at presentation, years of disease at colectomy, or indications for colectomy. CONCLUSIONS: Patchy or absent inflammation of the rectum and sigmoid can be present in untreated children with UC at disease onset. Because such children may be mistakenly diagnosed as having CD, these data must be considered when treatments or clinical research protocols are designed to include children with colitis.