Clinical Presentation and Evaluation

The pineal gland is a diencephalic diverticulum that is composed of primary pineal cells (pineocytes), glial cells, displaced germ cells and meningeal cells. Each of these cell types can undergo neoplastic transformation (Table 5). The clinical presentation of pineal region tumors falls into 3 typical patterns: (1) hydrocephalus related to the obstruction of the CSF pathways at the level of the aqueduct of Sylvius, (2) compression of local structures, or (3) endocrine dysfunction in the event of hypothalamic invasion. Hydrocephalus is the most common presentation, and children will present with vomiting, headache, or failure to thrive. The typical visual-movement abnormality seen with both hydrocephalus and compression of the tectal plate is failure of upward gaze, or Parinaud's syndrome.

Table 5. Histological types of tumors and masses arising in the pineal region

Tumors of pineal parenchymal cells

Pineoblastoma; pineocytic or

retinoblastomatous differentiation

Pineocytoma; astrocytic, neuronal

or mixed differentiation

Tumors of germ cell origin

Germinoma (dysgerminoma, seminoma,

atypical teratoma)

Embryonal carcinoma (totipotent)

Endodermal sinus tumor

(extraembryonic structures)

Choriocarcinoma (extraembryonic)

Teratoma (the only tumor in this group

either malignant or benign)

Tumors of glial and other cell origin

Astrocytoma

Glioblastoma

Ependymoma

Oligodendroglioma

Choroid plexus papilloma

Meningioma

Hemangiopericytoma

Metastases

Nonneoplastic cysts and masses

Pineal cysts (common incidental finding

on autopsy or MRI)

Cavernoma

Epidermoid cysts

AVM

Vein of Galen aneurysm

Inflammatory lesions (e.g., abscess, TB)

Since spread through the CSF pathways is a common feature of specific histological types, a spinal MRI, in addition to a detailed cranial MRI, is mandatory early in the evaluation (Chapter 2, Figs. 35-37). Serum and CSF is sampled for the presence of specific proteins. Alpha feto-protein is a glycoprotein produced by fetal-yolk-sac elements, typically endodermal sinus tumors (>1,000 ng/mL), although mild elevations are seen with embryonal-cell carcinoma and immature teratoma. Beta human chorionic gonadotrophin (p-hCG) is produced by placental tropho-blastic tissue, is typically elevated in choriocarcinoma (>2,000 ng/mL), and is mildly elevated in embryonal cell carcinoma and germinoma. Elevation of placental alkaline phosphatase (PLAP) is reported to be a relatively specific finding for germinoma, although its sensitivity is questionable.

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