During the last decade, complexity in head and neck pathology has been growing fast through the identification of new tumoral entities.
These new entities are mainly rare tumors that need to be recognized: specific immunohistochemistry and targeted molecular biology is often required.
This is especially true for undifferentiated sinonasal carcinomas and for tumors of salivary glands.
Despite their rarity, undifferentiated sinonasal carcinomas and tumors of salivary glands show a diversity that is unparalleled in comparison by any other organ.
This leads to a difficult differential diagnose between benign and malignant tumors with a major implication in patient treatment.