We identified a classification system based on gene expression analysis of formalin-fixed PDA samples. We identified 5 PDA subtypes, based on features of cancer cells and the tumor microenvironment. This system might be used to select therapies and predict patient outcomes. We found evidence that the previously reported exocrine-like (called ADEX) tumor subtype resulted from contamination with pancreatic acinar cells. ArrayExpress accession number: E-MTAB-6134.

BackgroundSchwannomas of the colon and rectum are rare among gastrointestinal schwannomas. They are usually discovered incidentally as a submucosal mass on routine colonoscopy and diagnosed on pathologic examination of the operative specimen. Little information exists on the diagnosis and management of this rare entity.The aim of this study is to report a case of cecal schwannoma and the results of a systematic review of colorectal schwannoma in the literature.Main bodyPubMed, Scopus, and Cochrane database searches were performed for case reports and case series of colonic and rectal schwannoma.Ninety-five patients with colonic or rectal schwannoma from 70 articles were included. Median age was 61.5 years (59% female). Presentation was asymptomatic (28%), rectorrhagia (23.2%), or abdominal pain (15.8%). Schwannoma occurred in the left and sigmoid colon in 36.8%, in the cecum and right colon in 30.5%, and in the rectum in 21.1%. Median tumor size was 3 cm and 56.2% of patients who underwent preoperative colonoscopy had a typical smooth submucosal mass. At pathology, 97.9, 13.7, and 5.3% of schwannomas stained positive for S100, vimentin, and GFAP, respectively. The median mitotic index was 1/50.ConclusionsColorectal schwannoma is a very rare subtype of gastrointestinal schwannoma which occurs in the elderly, almost equally in men and women. Schwannoma should be included in the differential diagnosis of a submucosal lesion along with gastrointestinal stromal tumor, neuro-endocrine tumors, and leiomyoma-leiomyosarcoma. Definitive diagnosis is based on immunohistochemistry of the operative specimen. Rarely malignant, surgery is the mainstay of treatment.

Abstract. Background In patients with colorectal cancer (CRC), the accurate establishment of the pathological status of tumor-draining mesenteric lymph nodes (LN) is of central importance for therapeutic management. In patients with stage III disease with demonstrated LN metastases, adjuvant systemic chemotherapy is indicated, reducing the risk of recurrence and improving long-term overall survival (1). The accuracy of mesenteric nodal staging depends primarily on the number of resected LN, and the seventh American Joint Committee on Cancer (AJCC) edition recommends harvesting and analysis of at least 12 to 14 LN for correct staging (2). Despite this, 20-30% of patients with no LN metastases demonstrated at pathology (pN0), and therefore classified as stage II, still develop recurrent disease (3). These recurrences could potentially be associated with unrecognized locoregional nodal metastases, which could lead to understaging and undertreatment.The sentinel lymph node (SLN) is defined as the first LN draining the primary tumor. In melanoma and breast cancer, it has been shown that pathological status of the SLN is indicative of the risk of nodal metastases, thus providing an indication for lymphadenectomy when SLN pathological examination is positive and for avoiding mutilating surgery when it is negative (4, 5). The concept, and potential utility, of the SLN is different in CRC since mesenteric lymphadenectomy is systematically performed during surgery for the primary tumor. In patients with CRC, the particular contribution of SLN examination could be to focus the pathological analysis specifically on draining LNs in order to improve the sensitivity for cancer cell detection by the use of advanced methods, such as serial sectioning, immunohistochemistry (IHC), and molecular analyses such as reverse transcriptase polymerase chain reaction (RT-PCR) to increase pathological staging (6).Accordingly, a recent meta-analysis concluded that the use of SLN examination allowed for nodal up-staging of patients with CRC, providing a potential benefit (7). However, the technique of SLN analysis is still not widely used in patients with CRC. This could be related to the variability of the sensitivity of techniques for SLN detection which ranges from 33% to 100%, to the risk of missed metastases, and also to uncertainty related to the clinical significance and prognostic value of nodal micrometastases in CRC (7-9).Recently, fluorescence imaging (FI) using indocyanine green (ICG) has emerged as a new technique for SLN detection in various tumors (10)(11)(12). Only few studies have 4853