Basic Neuroscience · Neuropathology
Neuro-oncology Pathology
CNS tumor pathology — pathognomonic histological findings, then each tumor's clinical picture, imaging, and biopsy appearance. The downloadable PDF includes the corresponding stained histology slides.
Pathognomonic findings
| Pathological finding | Tumor |
|---|---|
| Perivascular pseudorosette | Ependymoma, SEGA |
| Rosenthal fibers | Pilocytic astrocytoma |
| Rosettes (Homer-Wright) | Medulloblastoma |
| Wet keratin | Craniopharyngioma |
| Psammoma bodies | Meningioma |
| "Fried egg" cells | Oligodendroglioma |
CNS tumors
| Tumor | Clinical & imaging | Pathology |
|---|---|---|
| Medulloblastoma | Children; midline cerebellum; diffuse contrast enhancement. Can seed in CSF ("drop mets") but rarely involves meninges. MRS shows choline and taurine peaks. | Stains positive for synaptophysin; rosette formation. |
| Pilocytic astrocytoma | Children; cystic with an enhancing mural nodule. Can occur in the optic tract in NF1. Associated with BRAF mutation. | Cells with long processes; Rosenthal fibers (intense red deposits of hyaline). Hair-like processes arranged in bundles resembling mats of hair. |
| SEGA | In tuberous sclerosis (TSC1 on ch 9q34, TSC2 on ch 16). | Large polygonal cells with abundant eosinophilic cytoplasm; perivascular pseudorosettes. |
| Oligodendroglioma | Adults; lobar; associated with IDH mutation. Anaplastic (grade III) associated with allelic loss at 1p and 19q. | Rounded nuclei, prominent cytoplasm with a clear halo ("fried egg"). |
| Colloid cyst | Usually arises in the 3rd ventricle near the foramen of Monro. MRI: isointense on T1, hyperintense on T2. | Simple cuboidal or columnar epithelium, full of proteinaceous material. |
| Ependymoma | Usually arises in the 4th ventricle (children) or spinal cord (adults). Can seed through CSF. | Perivascular pseudorosettes — ependymal cell processes directed toward the vessel wall, with anuclear zones of GFAP+ fibrillary processes. |
| Subependymoma | Arises in the 4th ventricle in adults; does not enhance. | Clusters of cells embedded in a dense glial fibrillary background; pseudorosettes may be present. |
| Hemangioblastoma | Cystic cerebellar tumor in adults with a nodule of blood vessels; can involve the spine in VHL. | Vacuolated cells and vascular structures — packed thin-walled vessels and large neoplastic cells with pink-to-clear cytoplasm containing fine PAS+ lipid vacuoles. |
| Meningioma | Extra-axial dural-based mass. | Psammoma bodies (laminated calcific concretions) and whorl formation (cells arranged in whorls). |
| Choroid plexus papilloma | Arises in the lateral ventricle in children; homogeneous enhancement. | Papillary or villous architecture — a single layer of epithelial cells overlying a fibrovascular core. |
| Pituitary adenoma | Sellar mass. | Rounded or polygonal cells with rounded nuclei; cytoplasm chromophobic, acidophilic, or basophilic according to hormone production. |
| Craniopharyngioma | Suprasellar tumor in children; usually calcified. | Keratinocytes in spheres ("wet keratin"). |
| Rathke's cleft cyst | Suprasellar cystic tumor; isointense, non-enhancing. | Cyst lined with ciliated columnar epithelium with goblet cells. |
| Hypothalamic hamartoma | In children; causes gelastic seizures and precocious puberty. MRI: non-enhancing, isointense. | Hypocellular mass of mature glia and neurons. |
| Germinoma | Suprasellar or pineal (most common pineal tumor). | Small reactive lymphocytes and large neoplastic germ cells. |
| Pineocytoma | Adults; low-grade tumor; contrast enhancing. | Large anuclear areas called pineocytomatous rosettes. |
| DNET | Children or young adults. MRI: cortical, "soap bubble" appearance, no enhancement. | Glioneuronal tumor with a specific glioneuronal element. |
| CNS lymphoma | Usually arises at the edge of the ventricle. MRI: homogeneous enhancement, vasogenic edema on T2, diffusion restriction on DWI. | Angiocentric proliferation of atypical lymphoid cells. |
| Epidermoid cyst | Caused by entrapment of ectodermal tissue in the neural tube during development. MRI: CSF signal on T1/T2, heterogeneous on FLAIR, restricted diffusion (unlike arachnoid cyst). | Cyst lined by squamous epithelium, filled with keratin and cholesterol. |
LIGHTS on RITE by Ahmed Koriesh