Medulloblastomas occur in the cerebellum and usually arise from the vermis. They have a tendency to seed the cerebrospinal fluid and result in "drop metastases" in the spinal cord. This gross specimen photograph of a medulloblastoma shows a soft, fleshy tumor with areas of softening and necrosis in the center. Although the tumor appears well-circumscribed, there is usually some infiltration at the edges into the surrounding brain parenchyma. Image courtesy of: Dr. Jean-Christophe Fournet, Paris, France.