TUMOURS OF MAL-DEVELOP-MENTAL ORIGIN
Germinoma: Primitive spheroidal cell tumour comparable to seminoma of the testis. Teratoma: A tumour containing a mixture of well differentiated tissues - dermis, muscle, bone.
uncommon tumours of the pineal region (not arising from pineal cells)
- Craniopharyngioma: Arises from cell rests of buccal epithelium and lies in close relation to the pituitary stalk. Usually a nodular tumour with cystic areas containing greenish fluid and cholesteatomatous material.
-Epidermoid/dermoid cysts: Rare cystic tumours arising from cell rests predetermined to form epidermis or dermis.
- Colloid cyst: A cystic tumour arising from an embryological remnant in the anterior roof of the 3rd ventricle.
— Pituitary adenoma: Benign tumour, usually secreting excessive quantities of prolactin, growth hormone, adrenocorticotrophic hormone, thyrotropin or gonadotropin
I-» Adenocarcinoma: Malignant tumour occasionally arises in the pituitary.
■ Chordoma: Rare tumour arising from cell rests of the notochord. May occur anywhere from the sphenoid to the coccyx - but commonest in the basi-occipital and the sacrococcygeal region, invading and destroying bone at these sites.
- Glomus jugulare tumour (syn. chemodectoma): Vascular tumour arising from 'glomus jugulare' tissue lying cither in the bulb of the internal jugular vein or in the mucosa of the middle ear. The tumour invades the petrous bone and may extend into the posterior fossa or neck.
^ Other local tumours include chondroma, chondrosarcoma and cylindroma
Primary malignant lymphoma (syn. microgliomatosis): Forms around periventricular parenchymal blood vessels. May be solitary or multifocal. It generally occurs in immunocompromised patients, e.g. AIDS. Metastatic spread from systemic lymphoma (e.g. non-Hodgkin's lymphoma) is less common, involves the meninges and is rarely intraparenchymal.
Metastatic tumours: May arise from any primary site but most commonly spread from the bronchus or breast. Nervous system metastases occur in 25% of patients with disseminated cancer.
Immunohistochemical techniques permit identification of antigens specific for certain cell or tissue characteristics and aid the histological diagnosis of tumours.
e.g.Glial fibrillary acidic protein (GFAP) - for glial tumours
Epithelial membrane antigen (EMA)
Some markers also indicate the degree of proliferation in various tumours (e.g. Ki-67). The identification of growth factors (e.g. Epidermal growth factor (EGRF)) may help differentiate high-grade from low-grade tumours.
for metastatic carcinoma
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