A forum dedicated to the expansion in neuropathology knowledge for students and practitioners alike.
Pilocytic Astrocytoma (PA) characteristically exhibits biphasic morphology featuring densely fibrillar, compact regions alternating with loosely-cohesive microcystic or myxoid areas; the latter is pictured here. Diagnosis can be difficult, especially on small biopsies, but molecular testing can help. BRAF-KIAA1549 fusion occurs in about 70% of PAs, whereas BRAF V600E mutation occurs in about 5-10% of PAs.
Pilocytic astrocytoma is a circumscribed glioma (WHO Grade I) commonly found in children and young adults. Characteristic features include piloid cells with long, thin, hair-like cytoplasmic processes and a myxoid background, which are both seen here in this medium power image of a cytologic smear preparation performed during intraoperative consultation.
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 →
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 →
Neurofibrillary tangles, like the one shown here, are composed of hyperphosphorylated tau proteins. Intracellular neurofibrillary tangles and extracellular amyloid plaques comprise the two characteristic neuropathologic findings of Alzheimer Disease, the most common neurodegenerative disease associated with progressive memory loss. This image was taken from an area of the brain that is often affected in Alzheimer Disease: the hippocampus, which is a... Continue Reading →
Epidermoid cysts (pictured here with surrounding brain tissue) are histologically characterized by a thin layer of squamous epithelium similar to the epidermal lining the skin. However, unlike skin (which sheds its outer layer of dead cells into the environment), the keratin debris of the sloughed-off upper layer of the epidermoid cyst build up within the cyst center resulting in... Continue Reading →
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 →
Tuberculosis, or TB, is characterized by the formation of granulomas that often have central necrosis, called caseous necrosis due to its cottage-cheese appearance on gross evaluation. Caseating granulomas characteristically have central necrosis surrounded by an immediate layer of macrophages and inflammatory cells, which, in turn, are surrounded by proliferating fibroblasts. This effort to contain the... Continue Reading →
Histopathological diagnosis of Peripheral Neuroblastic Tumors explained (i.e. Neuroblastoma, Ganglioneuroblastoma, and Ganglioneuroma), with an example review of Ganglioneuroma. https://youtu.be/w9FEXK8tvJg
Diffuse axonal injury: Trauma that is strong enough to break long slender blood vessels is usually strong enough to break long delicate axons, too. Therefore, the presence of gross microhemorrhages in long white matter tracts, such as the corpus callosum, strongly suggests that diffuse axonal injury will be seen on microscopic evaluation of the axons comprising these white matter tracts. The image shows... Continue Reading →
Adventures in Neuropathology 