Pineal teratoma
Synonyms and keywords: Pineal teratomas; Pineal teratoblastoma ; Pineal teratoid tumor; Pineal germ cell tumors; Pineal gland tumors; Brain tumor

# Overview
Pineal teratoma is an uncommon extra-axial intracranial cancer, which can have varied components and thus a wide range of appearances. The most frequent location of these tumors is pineal and suprasellar region. Clinical signs and symptoms depend on the localization of the tumor. Most commonly include signs of increased intracranial pressure, Parinaud's syndrome, bitemporal hemianopsia and signs of endocrine deficiency. Mature teratomas are benign, mature, well-differentiated cystic lesions; whereas immature teratomas are poorly differentiated lesions with solid components and malignant transformation. Symptoms of pineal teratoma include headache, vomiting, somnolence, and weakness. Compression of the superior colliculi by pineal teratoma can lead to a characteristic gaze palsy, known as Parinaud syndrome.

# Classification
- Pineal teratoma may be classified into three sub-types:
Mature
Immature
Mature with malignant transformation
- Mature
- Immature
- Mature with malignant transformation
- Mature teratomas are benign, mature, well-differentiated cystic lesions; whereas immature teratomas are poorly differentiated lesions with solid components and malignant transformation.
- On other occasions, mature teratomas contain elements that undergo malignant transformation (most commonly squamous components).
Fat
Cystic spaces due to mucus production or other exocrine products
Soft-tissue from any part of the body
Calcification, including teeth
- Fat
- Cystic spaces due to mucus production or other exocrine products
- Soft-tissue from any part of the body
- Calcification, including teeth

# Pathophysiology
- On microscopic histopathological analysis, pineal teratoma is characterized by cells originating from at least two and usually all three embryonic layers (ectoderm, mesoderm, and endoderm). The histological subtype may not necessarily determine the biological behavior.

# Natural history, complications, and Prognosis
- Pineal teratomas may be associated with elevated levels of serum alpha fetoprotein (AFP) or serum carcinoembryonic antigen (CEA).
- Pineal teratoma must be differentiated from pineal lipoma, pineal dermoid, and other pineal gland tumors.
- Pineal teratoma is a rare disease that tends to affect the children and young adult population.
- Common complications of pineal teratoma include:
Obstructive hydrocephalus
- Obstructive hydrocephalus
- Head CT scan and brain MRI may be helpful in the diagnosis of pineal teratoma. Given their extremely variable histological components, CT/MRI imaging also tends to be heterogeneous, with tumors typically demonstrating a mixture of tissue densities and signal intensity. Fat, if present, is helpful in narrowing the differential.
- On head CT scan, pineal teratoma is characterized by a mass with fat and calcification, which is usually solid / "clump-like". It usually has cystic and solid components, contributing to an irregular outline. Solid components demonstrate variable enhancement on contrast administration.
- On brain MRI, pineal teratoma is characterized by:

# History and Symptoms
- The clinical presentation of pineal teratoma is mainly from the obstructive hydrocephalus secondary to compression of the tectum of the midbrain and obstruction of the aqueduct.
- Symptoms of pineal teratoma include headache, vomiting, somnolence, and weakness.
- Compression of the superior colliculi by pineal teratoma can lead to a characteristic gaze palsy, known as Parinaud syndrome.

# Treatment
- The mainstay of therapy for immature pineal teratoma is combined radiotherapy and chemotherapy.
- The residual or mature component is removed surgically.