The composition of biliary sludge varies. The most common particulate matter in biliary sludge is cholesterol crystals and calcium salts. Occasionally drugs may comprise the particulate matter since bile is one of the major routes for excretion of drugs. Tumefactive demyelinating lesion (TDL) is defined as a solitary de-myelinating lesion greater than 2 cm. Mass effect and contrast enhancement on neuroimaging make it difficult to distinguish this type of lesion from high-grade gliomas.