Making routine head and neck pathology Easy: From dissection to diagnosis

Resections from the mobile tongue, the oropharynx and neck dissections constitute a large proportion of routine head and neck pathology workload. Histologically detected proximity to margins and prognostic factors like depth of invasion, perineural or lymphovascular invasion, or extranodal extension guide adjuvant radiotherapy and/or chemotherapy. This review discusses practical approaches to macroscopic examination of the various types of tongue and oropharyngeal resections and neck dissections. Differential inking and radial sections demonstrate proximity of tumour to margins. The macroscopic examination and sampling should then be directed towards identifying remaining adverse prognostic features including the maximum extent of invasion at the primary site and extranodal extension, nodal matting or soft tissue deposits in the neck dissections. The diagnostic challenges differ in the tongue and oropharynx. The diagnosis of tongue SCC is relatively easy, however, precursor oral epithelial dysplasia can be challenging. Architectural and cytologic clues assisting in identifying dysplasia and practical clues distinguishing it from reactive changes are discussed. In contrast, dysplasia is not diagnosed in the oropharynx. p16 immunostaining and detection of human papillomavirus (HPV) play a critical role in the diagnosis and prognosis of oropharyngeal SCC. Nuances in the implementation and interpretation of p16 immunostaining and HPV assays are discussed.