A practical guide to serrated appendiceal lesions.

Several neoplastic and non-neoplastic proliferations of the appendix can show varying degrees of serrated epithelial architecture. Of these, diffuse mucosal hyperplasia is most common, followed in frequency by low-grade mucinous and serrated neoplasms. It is important to distinguish serrated appendiceal neoplasms from their potential mimics because these entities may be managed differently. Diffuse mucosal hyperplasia is a non-neoplastic change that usually develops in the setting of resolving appendicitis and requires no further therapy or surveillance, and serrated neoplasms confined to the mucosa are adequately treated by appendectomy alone. On the other hand, low-grade appendiceal mucinous neoplasms may require surveillance, and those with extra-appendiceal spread differ from adenocarcinomas arising from serrated neoplasms with respect to both treatment and prognosis. Low-grade mucinous neoplasms in the peritoneum are frequently amenable to peritoneum-directed therapies alone, while adenocarcinomas derived from serrated neoplasms often spread to both regional lymph nodes and the peritoneum, potentially requiring right colectomy and systemic chemotherapy. The purpose of this review is to summarize the literature regarding the clinical and pathologic features of appendiceal lesions that show epithelial serration and provide the reader with helpful tips to distinguish serrated neoplasms from their mimics.

Molecular Insights Into Colorectal Carcinoma.

Colorectal carcinoma (CRC) is one of the most common type of cancers and a leading cause of cancer-related deaths worldwide and in the United States. CRC is a heterogeneous disease with a well-characterized stepwise accumulation molecular alteration associated with adenoma formation and progression to carcinoma. We review the genomic and epigenomic pathways, including chromosomal instability, microsatellite instability, and epigenetic instability or CpG island methylator phenotype, their characteristics, and prognosis. We describe the four consensus molecular subtypes of CRC established by the international Colorectal Cancer Subtyping Consortium, their mechanisms to develop cancer, molecular characterization, clinical features, and prognosis. Finally, we review currently used predictive biomarkers.