They are a yellowish-brown color and are generally cylindrical with sometimes ragged edges; their fragility makes inspection of a fresh sample necessary. They are usually associated with nephritic syndromes or urinary tract injury. White blood cell casts
Indicative of inflammation or infection, the presence of white blood cells within or upon casts strongly suggests pyelonephritis, a direct infection of the kidney. They may also be seen in inflammatory states, such as acute allergic interstitial nephritis, nephrotic syndrome, or post-streptococcal acute glomerulonephritis. White cells sometimes can be difficult to discern from epithelial cells and may require special staining. Differentiation from simple clumps of white cells can be made by the presence of hyaline matrix. Bacterial casts
Given their appearance in pyelonephritis, these should be seen in association with loose bacteria, white blood cells, and white blood cell casts. Their discovery is likely rare, due to the infection-fighting efficiency of neutrophils and the possibility of misidentification as a fine granular cast. Epithelial cell casts
This cast is formed by inclusion or adhesion of desquamated epithelial cells of the tubule lining. Cells can adhere in random order or in sheets and are distinguished by large, round nuclei and a lower amount of cytoplasm. These can be seen in acute tubular necrosis and toxic ingestion, such as from mercury, diethylene glycol, or salicylate. In each case, clumps or sheets of cells may slough off simultaneously, depending on the focality of injury. Cytomegalovirus and viral hepatitis are organisms that can cause epithelial cell death as well. Eosinophilic cast
This type of cast contains eosinophils.
Variably protease-sensitive prionopathy (VPSPr) (formerly known as Protease Sensitive Prionopathy) is a sporadic prion protein disease first described in an abstract for a conference on prions in 2006, and this study was published in a 2008 report on 11 cases. The study was conducted by Gambetti P., Zou W.Q., and coworkers from the United States National Prion Disease Pathology Surveillance Center. It was first identified as a distinct disease in 2010 by Zou W.Q. and coworkers from the United States National Prion Disease Pathology Surveillance Center.VPSPr is very rare, occurring in just 2 or 3 out of every 100 million people. As of 2018, fourteen cases have been reported in the UK. It has similarities to Creutzfeldt–Jakob disease, but clinical manifestations differ somewhat, and the abnormal prion protein (PrP) is less resistant to digestion by proteases; some variants are more sensitive to proteases than others, hence the name: variably protease-sensitive. Patients present with behavioral and psychiatric symptoms, speech deficits (aphasia and/or dysarthria) and progressive cognitive and motor decline (dementia, ataxia, parkinsonism, psychosis, aphasia and mood disorder). Average age at onset is 70 years, and duration of survival is 24 months. About 40% of patients have a family history of dementia. Like CJD, it can be mistaken for Alzheimers dementia.