Undifferentiated and dedifferentiated head and neck carcinomas

Area of Science:

• Pathology
• Oncology
• Head and Neck Surgery

Background:

• Undifferentiated carcinomas in the head and neck can arise de novo or from dedifferentiation of known carcinomas.
• Classification relies on identifying differentiated components, specific genotypes (e.g., NUTM1 fusions), or viral associations (HPV, EBV).
• These tumors present diagnostic challenges, particularly in small biopsy samples.

Purpose of the Study:

• To review and discuss the diagnostic approach for head and neck carcinomas with undifferentiated morphology.
• To highlight key diagnostic features, including genetic drivers and viral associations.
• To focus on salivary gland, oropharyngeal, nasopharyngeal, and sinonasal subsites.

Main Methods:

• Literature review of diagnostic strategies for undifferentiated head and neck carcinomas.
• Analysis of classification criteria based on morphology, genetics, and viral markers.
• Focus on challenging cases, including those from small biopsies.

Main Results:

• Undifferentiated carcinomas require identification of specific genetic drivers (e.g., NUTM1 fusions) or viral associations (HPV, EBV) for classification.
• Dedifferentiation of known carcinomas or de novo origin influences diagnostic pathways.
• Diagnostic approaches vary based on tumor subsite (salivary gland, oropharyngeal, etc.).

Conclusions:

• Accurate diagnosis of undifferentiated head and neck carcinomas relies on integrating morphological, genetic, and virological data.
• Recognizing specific genetic drivers and viral associations is crucial for subtyping and guiding treatment.
• A systematic diagnostic approach is essential for managing these challenging tumors, especially in limited biopsy material.