Crohn's colitis-like changes in sigmoid diverticulitis specimens is usually an idiosyncratic inflammatory response to the diverticulosis rather than Crohn's colitis.

The clinical outcome and optimum classification of patients who have sigmoid resection specimens that show the histologic features of Crohn's disease (CD) and diverticulitis is not well defined. Historically, these patients were considered to have coexistent diseases, but recent studies have suggested that the CD-like changes are part of the inflammatory reaction of the diverticulitis. Sorting out these issues has been complicated by the lack of distinction between patients with and without CD in other regions of the bowel, short clinical follow-up periods, and small numbers of patients. We report on the clinical outcome and histology of 29 patients who had sigmoid resection specimens with diverticulitis and CD-like changes. Of the 25 patients who had no prior or concurrent CD at the time of surgery, 23 remained free of CD during the follow-up period (median, 6.0 yrs) and two developed CD in other regions of the bowel. All four patients with CD prior to their sigmoid resection continued to have active CD postoperatively. There were no histologic features of the sigmoid resection specimens that could be associated with the outcome of the patient. These results suggest that CD-like changes within the sigmoid resection specimen are an idiosyncratic inflammatory response to the diverticulosis rather than coexistent CD in the overwhelming majority of patients who do not have prior or concurrent CD at the time of sigmoid resection. Pathologists should be wary about making the diagnosis of sigmoid CD in the context of diverticulitis unless there is CD in other parts of the bowel.

Histopathologic and flow-cytometric analysis of neoplastic and benign "background" tissue in breast carcinoma resections.

Two-color, multiparametric synthesis phase fraction (SPF) analysis of cytokeratin-labeled epithelial cells was flow cytometrically performed on both benign (SPFb) and malignant tissue samples (if available, SPFt) from 132 mastectomy/lumpectomy specimens. These data were then correlated with clinicopathologic features, including (1) tumor differentiation, (2) the proportion of tumor comprised of duct carcinoma-in situ (DCIS), and (3) the histology of accompanying benign breast tissue, classified by predominant microscopic pattern as intact, normal terminal duct lobular units (NTDLU, 34% of cases), atrophic (AT, 33% of cases), proliferative fibrocystic (PFC, 26% of cases), and non-proliferative fibrocystic (NPFC, 7% of cases). SPFt was inversely correlated with extent of DCIS (DCIS = 0-20% tumor volume - 12.7% mean SPFt, vs. DCIS >20% tumor volume - 6.4% mean SPFt, p = 0.001). SPFt also correlated with the histology of background benign breast tissue (NTDLU - 14.8% mean SPFt vs. AT - 6.9% mean SPFt vs. PFC - 12.7% mean SPFt, p = 0.05) but it did not correlate with patient age or SPFb (overall mean = 0.73%). SPFb was correlated with patient age (>56 yr - 0.59% mean SPFb vs. <56 yr - 0.84% mean SPFb, p = 0.02), with background histology (NTDLU - 1.1% mean SPFb vs. AT - 0.43% mean SPFb vs. PFC - 0.70% mean SPFb, p < 0.02) and with the grade of the neoplasm (well/moderate - 0.58% mean vs. poorly differentiated - 0.85% mean, p = 0.04). Patients having a background of PFC were significantly older than patients with a background of NTDLU (45.2 yr vs. 60.2 yr, p = 0.01). We conclude: (1) breast carcinomas arising from a background of more actively cycling pre-involutional or proliferative fibrocystic epithelium have a greater proliferative fraction than tumors arising from atrophic epithelium, implying that the differentiation status of target cells may impact the effect(s) of tumorigenic events; (2) PFC may represent delayed, abnormal or interrupted involution rather than a hyperproliferative state relative to NTDLU, suggesting that it facilitates neoplasia by extending the period of exposure to promoter agents such as endogenous hormones, and (3) lower SPFt in breast neoplasia with more abundant "residual" DCIS may reflect a lengthier pre-invasive disease interval due to intrinsically less aggressive phenotype.