Spongiform

Spongiform is a descriptive term used in pathology to describe tissue that has a sponge-like appearance because of numerous small vacuoles or cavities within the tissue. The term is most often applied to brain tissue, where the vacuolation creates a porous, spongy look under light microscopy. It is a morphological feature rather than a disease in itself.

In the context of prion diseases, spongiform changes refer to vacuolation of the gray matter neuropil and, less commonly, neuronal bodies. These changes result from the abnormal folding and accumulation of prion proteins, and they are typically accompanied by neuronal loss and gliosis. Spongiform degeneration is considered a hallmark of many prion diseases, though its extent and distribution can vary by disorder.

Examples of conditions associated with spongiform changes include bovine spongiform encephalopathy in cattle and scrapie in sheep and goats. In humans, spongiform changes are seen in prion diseases such as Creutzfeldt-Jakob disease and its variant form, as well as in historically documented illnesses like Kuru. Spongiform patterns can also be observed in other neurodegenerative or metabolic conditions, but they are most closely linked with prion-related pathology.

Diagnosis typically relies on histopathological examination of brain tissue, usually postmortem, to identify characteristic vacuolation. Confirmation and characterization may involve immunohistochemistry or biochemical assays to detect prion proteins. In living patients, diagnostic approaches increasingly incorporate laboratory tests that assess prion protein seeding activity, such as RT-QuIC, alongside clinical assessment.