Pineal Region Tumors (aka Pinealoma)
Overview
- Pineal region tumors comprise a wide range of tumor types (germ cell vs pineal parenchymal) that can be benign and surgically resectable or malignant and able to metastasize widely.
- They classically manifest initially with dorsal midbrain syndrome (a syndrome of upgaze palsy, convergence-retraction nystagmus, eyelid retraction, and light-near dissociation).
- Pineal tumors also manifest with posterior fossa (brainstem and cerebellum) compression symptoms, increased intracranial pressure due to obstructive hydrocephalus, and hypothalamic dysautonomia.
- Obstructive hydrocephalus: pineal region tumors may enlarge enough to obstruct CSF drainage from the 3rd ventricle into the cerebral aqueduct and cause hydrocephalus of the 3rd ventricle and lateral ventricles.
Pineal Region Tumor Types
Germ Cell Tumors
- Intracranial germ cell tumors (GCTs) typically arise in the pineal and suprasellar regions. The production of tumor-associated human chorionic gonadotropin (hCG) by a germinoma can lead to precocious puberty.
- Mature teratomas are typically surgically resectable
- Malignant germ cell tumors have an ability for widespread metastasis.
Pineal Parenchymal Tumors: Pineocytoma vs Pineoblastoma
- Pineocytoma (benign)
- More frequent in young adults (vs pineoblastomas, which are more common in children).
- Being benign, they are well demarcated, their histopathology shows low mitotic activity, and carry a better prognosis than pineoblastomas.
- Their cells resemble pineocytes.
- Pineocytomatous rosettes are similar to Homer Wright rosettes but are larger and more irregular.
- Pineoblastoma (malignant)
- More frequent in children (vs pineocytomas, which are more common in young adults).
- Being malignant, they are poorly demarcated, demonstrate hemorrhage and necrosis, are able to spread along the neuroaxis (brain/spinal cord), and carry a worse prognosis than pineocytes.
- Their histopathology is consistent with embryonal tumors (eg, medulloblastoma) rather than pineocytes and demonstrates characteristic features of malignancy (ie, high mitotic activity).
- Similar to embryonal tumors, they can manifest with Homer Wright rosettes and Flexner-Wintersteiner rosettes.
- Genetics: associated with chromosome 11q deletion.
Dorsal Midbrain Syndrome (aka Parinaud Syndrome)
Clinical Features
- Upgaze palsy with convergence-retraction nystagmus
- Meaning when the patient attempts to look up, there is convergent/retractory episodic jerking.
- Eyelid retraction
- Light-near dissociation
- The pupils do NOT respond to light but do constrict to near response.
- Do not confuse with Progressive Supranuclear Palsy (PSP), which presents initially with downgaze palsy (sunset sign) and ultimately with complete vertical gaze palsy.
References
- Adesina, Adekunle M., Tarik Tihan, Christine E. Fuller, and Tina Young Poussaint. Atlas of
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- Gray, Frangoise, Charles Duyckaerts, and Umberto De Girolami. Escourolle and Poirier’s Manual of Basic Neuropathology. OUP USA, 2013.
- Samuels, Martin A., Allan H. Ropper, and Joshua Klein. Adams and Victor’s Principles of Neurology 10th Edition. McGraw-Hill Education, 2014.
- Tonn, Jörg-Christian, Manfred Westphal, and J. T. Rutka. Oncology of CNS Tumors. Springer Science & Business Media, 2010.
- Yachnis, Anthony T., and Marie L. Rivera-Zengotita. Neuropathology E-Book: A Volume in the High Yield Pathology Series. Elsevier Health Sciences, 2012.