Person:

Le, Long Phi

Microsatellite instability (MSI) has been reported in various tumors, with colon cancer as the prototype. However, little is known about MSI in Barrett esophagus (BE)-associated adenocarcinoma. Thus, the aim of this study was to compare the clinicopathologic and molecular features of BE-associated adenocarcinomas with and without MSI. The study cohort consisted of 76 patients with BE-associated adenocarcinomas (66 male, 10 female), with a mean age of 65.1 years. Immunohistochemistry (IHC) for MLH1, MSH2, MSH6, PMS2, and CD3 and in situ hybridization for Epstein-Barr virus-encoded RNA were performed. MLH1 and PMS2 expression was lost by IHC in 5 cases (6.6%); of these, 5 showed high-level MSI (MSI-H) by polymerase chain reaction assay, and 4 showed hMLH1 promoter methylation. Histologically, tumors with MSI-H were heterogenous and included conventional adenocarcinomas with tumor-infiltrating lymphocytes (n=1), medullary carcinoma (n=2), signet ring cells (n=1), and signet ring cell and mucinous components (n=1). Compared with tumors negative for MSI by IHC, BE-associated adenocarcinomas with MSI-H were associated with older patient age (P=0.0060), lymphovascular invasion (P=0.027), and significantly larger numbers of tumor-infiltrating lymphocytes (P<0.0001). However, there was no statistical difference in overall survival between the 2 groups (P=0.285). In conclusion, MSI-H is uncommon in BE-associated adenocarcinomas, but is associated with clinicopathologic features fairly similar to sporadic microsatellite unstable colorectal cancers. Given the growing evidence that indicates lack of benefits from adjuvant therapy with fluorouracil in the colonic counterpart, it may be important to identify MSI-H in BE-associated adenocarcinomas.

Pancreatic acinar cystadenomas (ACAs) are rare cystic lesions showing acinar differentiation with benign outcome. Although debated, ACAs are favored to be neoplastic and potentially the benign counterpart of acinar cystadenocarcinoma. We present the largest single institution series to date comprising 10 cases. The mean age was 49 years with a female predominance (M:F=1:2.3). Abdominal/flank pain was the most common presentation (n=6). Serum amylase/lipase and cyst fluid amylase were often elevated. All lesions had a benign outcome on follow-up (5 to 67 mo). The lesions were unilocular (n=3) or multilocular (n=7) with mean size of 3.8 cm (range, 2.9 to 5.0 cm) and 5.1 cm (range, 2.0 to 7.5 cm), respectively. Eight lesions were unifocal with locations as follows: head (n=2), head/neck (n=2), body (n=1), tail (n=1), predominantly extrapancreatic with a microscopic intrapancreatic component (n=1), and unspecified location (n=1). Two lesions were multifocal, involving the head/uncinate/body and pancreatic head, respectively. Two aspects of ACAs that may represent a diagnostic pitfall include the propensity for acinar epithelium to appear as nondescript flat/cuboidal epithelium (trypsin/chymotrypsin immunopositive) and epithelial heterogeneity, with focal mucinous and squamous epithelium, the latter particularly in multilocular variants. In addition, 2 cases with intracystic nodules were observed. Array comparative genomic hybridization performed on 1 of these cases showed multiple chromosomal gains involving 1p, 3p, 5q, 6p, 7q, 8, 10q, 11, 14, 20, and X. These findings provide preliminary evidence that ACAs represent a cystic neoplastic lesion.