Tumefactive demyelination, intra

When a brain biopsy is performed, often the pathologist will do what is called a touch preparation or crush preparation: a sample of tissue is smeared onto a glass slide. This process destroys the structure of the tissue, but preserves the cell types. This could be useful, for example in allowing the pathologist to rapidly identify if the surgeon has biopsied the tissue of interest, and what kind of cells are present, before the skull is closed. In this crush preparation, lipid-laden macrophages are present, consistent with an active demyelinating plaque.