Pineal teratoma

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Sujit Routray, M.D. [2]

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.
• Pineal teratoma may be classified into three subtypes: mature, immature, and 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 mucous production or other exocrine products
• Soft-tissue from any part of the body
• Calcification, including teeth

• 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.
• 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

• 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.
• 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 bya 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:

MRI component	Findings
T1	Hyperintense components due to fat and proteinaceous/lipid-rich fluid Intermediate components of soft tissue Hypointense components due to calcification and blood products
T1 with contrast	Solid soft tissue components show enhancement
T2	Mixed signal from differing components

Treatment

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

Management Options of Penial Gland tumors
CSF diversion	The optimal surgical strategy to treat acute hydrocephalus in patients with pineal tumors is uncertain. CSF diversion (ventriculoperitoneal [VP] shunt or third ventriculostomy may be necessary in symptomatic patients, although debulking surgery may obviate the need for this procedure When CSF diversion is necessary, endoscopic third ventriculostomy can be carried out at the same time as the biopsy and is preferred over VP shunts, which can be complicated by infection, shunt malfunction, subdural hematoma, and rarely, tumor seeding
Surgical resection	Some series report long-term survival with surgery alone, even in patients with pineoblastomas. Indeed, for pineoblastomas, gross total surgical resection appears to correlate with improved survival. Patients with symptomatic recurrent pineocytomas should also be considered for surgical resection of the lesion
Radiation	Postoperative adjuvant RT is frequently (but not universally) recommended, and local control is dose-dependent. The incidence of leptomeningeal recurrence was significantly lower among patients receiving CSI compared with those who did not. The five-year survival rates were 86 and 49 percent for pineocytomas and non-pineocytoma PPTs, respectively. Adjuvant RT is not universally recommended after gross total resection of a pineocytoma
Stereotactic radiosurgery	Stereotactic radiosurgery (SRS) is emerging as a useful treatment alternative for pineocytomas, although experience is limited. The precise radiation fields that are defined by MRI or CT-computerized treatment planning minimize damage to the surrounding brain, and the risks of general anesthesia and craniotomy are avoided. SRS is increasingly being used to treat pineal region tumors, either as an additional therapy after conventional treatments or as a primary treatment. Due to the low rate of side effects, IRS may develop into an attractive alternative to microsurgery in de novo diagnosed pineocytomas. In malignant PPTs, IRS may be routinely applied in a multimodality treatment schedule supplementary to conventional irradiation.
Chemotherapy as part of multimodality therapy	The similarity of pineoblastomas to medulloblastomas in terms of their clinical behavior and tendency for leptomeningeal seeding has led to the use of similar chemotherapy regimens in patients with pineoblastoma as part of a multimodality approach. Chemotherapy has been used to delay radiation therapy in very young children, for whom the long-term neurocognitive and developmental side effects of craniospinal irradiation (CSI) are a major concern. The importance of radiation therapy as a component of the initial treatment of supratentorial primitive neuroectodermal tumors (PNETs) is also supported by the German HIT-SKK87 and HIT-SKK92 protocols, as well as the Canadian pediatric brain tumor protocol

References

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