What exactly is a heart attack? Most heart attacks happen when a clot in the coronary artery blocks the supply of blood and oxygen to the heart. Often this leads to an irregular heartbeat-called an arrhythmia-that causes a severe decrease in the pumping function of the heart.
Oncocytoma can be described as a tumor that is mainly constituted out of oncocytes. These are actually epithelial cells, containing excessive quantities of mitochondria. This excess leads to a cytoplasm that is acidophilic and granular.
A juvenile pilocytic astrocytoma (JPA) is a slow-growing brain tumor that develops â usually in children and adolescents â from cells called astrocytes. juvenile pilocytic astrocytoma is a cystic (fluid-filled) tumor, not a solid mass. On the World Health Organizationâs grading scale, a JPA is a Grade I tumor, highly unlikely to grow or to spread to other areas. Other types of gliomas in children include: 1  Fibrillary astrocytoma.