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A hamartoma is a mostly benign, [3] local malformation of cells that resembles a neoplasm of local tissue but is usually due to an overgrowth of multiple aberrant cells, with a basis in a systemic genetic condition, rather than a growth descended from a single mutated cell (monoclonality), as would typically define a benign neoplasm/tumor. [4]
Schwann cells or neurolemmocytes (named after German physiologist Theodor Schwann) are the principal glia of the peripheral nervous system (PNS). Glial cells function to support neurons and in the PNS, also include satellite cells, olfactory ensheathing cells, enteric glia and glia that reside at sensory nerve endings, such as the Pacinian corpuscle.
Cellular schwannoma is nearly exclusively made up of a fascicular proliferation of well-differentiated Schwann cells that are cytologically bland, missing Verocay bodies, and just slightly exhibiting Antoni B pattern growth (10% of the tumor area). [12] [13] [14] Local recurrence is Variable (5-40%) and perhaps greater than in normal schwannomas.
Schwann cells are glial cells that myelinate the axons of nerve cells. Myelin is a lipid covering that speeds the conduction of action potentials. When Schwann cells proliferate out of control in an encapsulation it is called a schwannoma. Although schwannomas are benign they become detrimental when the growing tumor compresses the nerve.
The Schwann cells that multiply to form a VS on the vestibulocochlear nerve were identified 60 years later in 1838 by the German physiologist Theodor Schwann. In 1895, Thomas Annandale , a general surgeon at the Royal Infirmary in Edinburgh , Scotland, was the first to successfully localize and surgically remove a VS. [ 43 ]
Schwann dedicated a chapter of the treatise to explicitly formulate the cell theory, stating that ("the elementary parts of all tissues are formed of cells” and that “there is one universal principle of development for the elementary parts of organisms... and this principle is in the formation of cells" (Henry Smith's translation, 1847).
Animals are all around us. Because of their proximity, many people take for granted how truly dangerous some animals really are. Let’s discuss the 10 most dangerous animals in the world ranked ...
A nervous system tumor is a tumor that arises within the nervous system, either the central nervous system (CNS) or the peripheral nervous system (PNS). [1] [2] Nervous system primary tumors include various types of brain tumor and spinal tumors, such as gliomas, and meningiomas (of the CNS), and schwannomas (of the PNS) and can be either benign or malignant.