Pathology and Differential Diagnosis of Anterior Skull Base Tumours.

The anterior skull base is a complex anatomic site which may be involved by a large number of biologically heterogenous neoplasms. They arise from the epithelium, both surface mucosa and glands, as well as soft tissues, bone, and cartilage. Many benign and malignant tumours in the anterior skull base are similar to their counterparts in other anatomic sites. Interestingly, unique tumours including teratocarcinosarcoma, olfactory neuroblastoma, and angiofibroma can also be found. Recognition of overlapping morphologic features of entities encountered in this anatomic site and the corresponding differential diagnosis is critical. The integration of both morphologic features and immunohistochemical evaluation is essential for correct diagnostic interpretation. This is particularly notable in small round blue cell tumours for which morphologic lineage differentiation is lacking, thus requiring immunohistochemical characterisation. Moreover, challenges in accessing tissue for diagnosis leads to limited biopsies that require proper handling for adequate assessment. Histologic evaluation combined with communication between surgeons and pathologists are necessary components in the work-up and evaluation of these rare tumours.