Ice Cream and Imaging: Typical Appearance of Vestibular Schwannoma

Cranial nerve schwannomas most commonly arise from Schwann cells that myelinate the distal aspect of the vestibular division of the 8th cranial nerve. Vestibular schwannomas, sometimes referred to by the double misnomer "acoustic neuroma" (it is a double misnomer because they are not neuromas and they do not usually involve the acoustic division of cranial... Continue Reading →

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Verocay Bodies in Schwannoma

Schwannomas are peripheral nerve sheath tumors that arise from cells that myelinate peripheral nerve axons called Schwann cells. A classic histologic finding in schwannomas are Verocay bodies (arrows), which consist of short palisades of tumor cell nuclei separated by eosinophilic anucleate bands of tumor cell processes.  Verocay bodies are often more prominent in schwannomas that arise in the setting of a... Continue Reading →

Oligodendroglioma: the ‘Fried Egg’ Brain Tumor

Oligodendrogliomas often show the classic “fried egg” appearance, in which each cell contains a small round monomorphic nucleus with a perinuclear region of clearing, as well as small delicate blood vessels, or “chicken-wire vasculature”.  The fried egg morphology is an artifact of formalin fixation and will not be observed in frozen tissue sections.  In addition,... Continue Reading →

Gemistocytic Astrocytoma

Astrocytomas (i.e. glial tumors that diffusely infiltrate through brain tissue) are composed of neoplastic astrocytes that may occasionally exhibit certain morphologic differences when observed microscopically. Gemistocytic astrocytes are characterized by eccentric nuclei and plump pink cytoplasm that superficially resembles the belly of a pregnant woman when viewed from above. Neoplasms that are predominantly composed of... Continue Reading →

Schwannoma Gross Appearance

Peripheral nerve fibers are sheathed by Schwann cells, which occasionally give rise to a Schwannoma (also termed neurilemoma), a circumscribed tumor that typically occurs along the peripheral aspect of a nerve.  Unlike neurofibromas, schwannomas often can be excised without sacrificing the parent nerve, leaving the patient functionally intact.  Depending on the degree of microscopic microcystic changes, schwannomas can have a soft... Continue Reading →

Spinal Ependymoma: Typical Radiographic Appearance

Ependymal tumors are the third most common primary spinal tumor in adults, after meningiomas and peripheral nerve sheath tumors.  WHO (World Health Organization) Grade II spinal ependymomas, like the one depicted on this sagittal MRI of the cervical spine, have a typical radiographical appearance featuring an intramedullary oval-shaped mass with contrast enhancement.  Ependymomas are often... Continue Reading →

Atypical Meningioma – Mitoses and Macronucleoli

The vast majority of meningiomas are benign grade I tumors.  Meningiomas can be upgraded to grade II, called atypical meningiomas, if they show increased mitotic activity (4 or more mitoses in 10 high power fields) or other worrisome histopathologic features, such as tumor cells exhibiting a prominent and large nucleolus.  Notice the mitosis in the center-right of the image and... Continue Reading →

Reactive vs. Neoplastic Astrocytes

Astrocytes are star-shaped glial cells that comprise a large proportion of brain tissue.  Non-neoplastic reactive astrocytes can sometimes be difficult to differentiate from the neoplastic astrocytes of glial tumors called astrocytomas.  This GFAP stain highlights the key morphologic differences between the star-shaped and widely spread-out non-neoplastic reactive astrocytes compared to the neoplastic astrocytes in this glioblastoma, which exhibit crowding and severe variation in... Continue Reading →

Giant Cell Glioblastoma and Granular Mitoses

Giant Cell Glioblastoma, also called magnocellular or monstrocellular glioblastoma, is characterized by atypical cells that are extremely large, especially when compared to the non-neoplastic inflammatory cells seen on the left side of the image.  The tumor has increased number of dividing cells, including typical mitotic figures (bottom left arrow) and atypical or granular mitoses (bottom... Continue Reading →

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