What constitutes a teratoma and how does it differ from a dermoid?
Teratomas are comprised of cells originating from at least two and usually all three embryonic layers : ectoderm, mesoderm and endoderm, where as dermoids contain only ectodermal structures. As such teratomas can contain essentially any type of tissue.
How are teratomas classified?
Intracranial teratomas can be divided into two broad categories A) intra-axial B) extra-axial; these differ in epidemiology and clinical presentation. Alternatively they can be divided into: 1) mature 2) immature 3) with malignant transformation.
Where are extra-axial teratomas usually located and what demographic is usually affected?
Extra axial teratomas usually present in childhood or early adulthood and are typically smaller. They most commonly arise in the pineal or suprasellar regions.
Where are intra-axial teratomas usually located and what demographic is usually affected?
Intra-axial teratomas are located within the cerebral tissue (they tend to occur more commonly supratentorially, within the cerebral hemispheres). They typically present either antenatally or in the newborn period. They are large tumours that increase head circumference and therefore often present with difficulty in child birth.
The patient went on to have a craniotomy and excision of the both the solid component and the fatty / calcified eccentric component.
MICROSCOPIC DESCRIPTION: Paraffin sections from specimens 1 to 3 show solid sheets of non-keratinizing squamous epithelium along with many fibrovascular stromal cores. The surrounding stroma is chronically inflamed. There is no cellular atypia. No calcification is identified. In specimen 4 some additional features are seen, which include sheets of mature fat intimately associated with mature bone and some fibrous tissue. A small island of mature bone is seen embedded within fat. These additional features, if confirmed to be intrinsic part of the tumour, are not seen in a craniopharyngioma.
FINAL DIAGNOSIS: Mature teratoma.