[Mucinous carcinomas across organs: Definitions, profiles, diagnostic pitfalls and practical implications for...

Mucinous carcinomas represent a cross-organ histologic subtype defined by the presence of abundant extracellular mucin, which is their main criteria of identification and definition. However, the terminology and diagnostic criteria proposed by the current international classifications vary according to the site. This heterogeneity makes it difficult to evaluate whether the morphological similarities observed across the organs are associated, or not, with biological, molecular and genetic similarities. The objectives of this review are: (a) to compare the criteria proposed by the current WHO classifications to make the diagnosis of mucinous carcinoma according to the site, (b) to describe, in the different locations, the main tumor entities, their immunophenotypes and their molecular profiles, and (c) to evaluate their prognostic and therapeutic implications. This synthesis will lead us to discuss the main diagnostic difficulties, to propose diagnostic algorithms and standardized immunohistochemical panels, and to list the minimal items to integrate into the final report.