Читать книгу Anterior Skull Base Tumors - Группа авторов - Страница 63

Ewing sarcoma and PNET are interrelated primitive round cell malignancies of neuron-ectodermal derivation [115–117]. They represent a spectrum of morphologic entities that share common molecular genetic features. These tumours rarely involve the skull base, mainly as a secondary extension from sinonasal localisations, and typically occur in childhood and young adults. The maxillary sinus and the nasal fossa are the most commonly affected sites. Grossly, tumours present as light-tan, soft, and fleshy tissues with haemorrhage and mucosal ulceration.

Table 5. Immunomarkers in the differentiation of small round cell tumours

Histologically, the tumour presents in sheet and nests of densely uniform small cell proliferation. CD99 (MIC2) is commonly used and generally positive. PCR-based methods to detect the EWS/FLI gene fusion transcript and in situ hybridisation of chromosomes t(11;22) or t(21;22) is helpful in confirming the diagnosis (Table 5).