Differential diagnoses The most common missed lesion is within the<unk>  cavity, where a fibrosed<unk>  polyp may be considered. However, it does not have<unk>  tissue. Further, a polyp usually has mucoserous glands. The lesion is frequently misinterpreted as scar in the subcutaneous tissues, but scar in a < 2-year-old child would be uncommon. Special stains are frequently required to highlight the diagnosis. Imaging findings There is a subcutaneous nodule identified just below the<unk>  bridge in this computed tomography image of a<unk> . Imaging studies are performed before surgery or biopsy to preclude an intracranial connection. Images usually show a sharply circumscribed but expansile mass. It may be difficult to exclude the intracranial connection if the defect is small whether employing computed tomography or magnetic resonance. Classification While<unk>  (NGH) is the preferred term, synonyms have included<unk>  glioma. However, this term is to be discouraged, as it implies a neoplasm or tumor, which it is not. By definition,<unk>  is a specific type of choristoma. It is not a teratoma, however, which is a neoplasm comprising all three germ cell layers (ectoderm, endoderm, mesoderm). As a congenital malformation or ectopia, it is distinctly different from the trauma or iatrogenic development of an encephalocele.
Nasal glial heterotopia
Basilar invagination
Gray matter heterotopia
Dysembryoplastic neuroepithelial tumour
Cranio-lenticulo-sutural dysplasia
Germinal matrix hemorrhage
Cystic hygroma
Choroid plexus papilloma