Faculty Bibliography

The PathfinderTG biomarker panel is useful in the evaluation of pancreatic cysts that have clinical features suspicious for malignancy, but its utility in classifying fine-needle aspiration biopsies from small pancreatic cystic lesions is yet to be proven. We used morphology to classify 20 pancreatic cyst cytology aspirates, all of which met radiographic criteria for close observation. Cases were cytologically classified as consistent with pseudocyst, serous cystadenoma, or mucinous neoplasm with low-grade, intermediate-grade, or high-grade dysplasia and analyzed for carcinoembryonic antigen. Redpath Integrated Pathology Inc. rendered diagnoses of nonmucinous (reactive/indolent or serous) or mucinous (low-risk or at risk) cyst on the basis of results of the PathfinderTG panel (KRAS mutations, DNA content, and loss of heterozygosity at microsatellites linked to tumor suppressor genes). Cytologic and commercial laboratory diagnoses were concordant in only 7 (35%) cases. Seven cysts classified as mucinous with low-grade dysplasia by cytology were interpreted as nonmucinous on the basis of the PathfinderTG panel, 2 of which were resected mucinous cysts. Two pancreatitis-related pseudocysts were misdiagnosed as low-risk mucinous cysts; 1 mucinous cyst with low-grade dysplasia was considered at risk for neoplastic progression using the PathfinderTG panel. Only 1 cyst misclassified as pseudocyst by cytology, but low-risk mucinous cyst by molecular analysis, proved to be a mucinous cystic neoplasm with low-grade dysplasia after surgical resection. We conclude that the PathfinderTG panel may aid the classification of pancreatic lesions, but is often inaccurate and should not replace cytologic evaluation of these lesions.

BACKGROUND: The incidence of rectal cancer in the United States in young patients is considered to be low. Underestimating this incidence may result in a failure to diagnose younger patients with rectal cancer in a timely manner. METHODS: The authors conducted a retrospective cohort study using Surveillance, Epidemiology, and End Results (SEER) cancer registry data. A total of 7661 patients with colon, rectal, and rectosigmoid cancer who were diagnosed at age <40 years were identified between 1973 and 2005. The change in incidence over time for colon and rectal/rectosigmoid cancer was calculated and the annual percent change for anatomic subsites of colorectal cancer compared. RESULTS: SEER data demonstrated an increase in the incidence of rectal cancer without any increase in colon cancer (annual percent change of 2.6% vs -0.2%). The difference was statistically significant and extended to rectosigmoid cancer, but not cancer of the sigmoid colon or descending colon (annual percent change of 2.2% vs 0.4% and -2.8%, respectively). Joinpoint analysis of the slope of the curve of rectal and rectosigmoid cancer incidence identified the beginning of the increase to be 1984. All races and both sexes demonstrated similar statistically significant increases in the incidence of rectal and rectosigmoid cancer. CONCLUSIONS: The incidence of rectal and rectosigmoid cancer appears to be increasing in patients aged <40 years. Patients presenting with rectal bleeding or other alarming signs or symptoms should be evaluated with this finding in mind.