hyalinos

Hyalinos, or hyaline material, refers to glassy, eosinophilic, homogeneous material found in tissues and fluids as a result of degenerative or secretory processes. The term derives from the Greek hyalos, meaning glass, and is used to describe a range of substances that appear glassy under light microscopy rather than a single uniform substance.

In pathology, hyalinos is most commonly encountered as hyaline change or hyaline deposition in various tissues. A well-known example is hyaline arteriolosclerosis, in which small arteries and arterioles develop a homogeneous pink hyaline thickening of the vessel wall, frequently seen in aging and diabetes mellitus. The change reflects leakage of plasma proteins into the vessel wall and increased deposition of basement membrane material. In the kidney, proximal tubular cells can accumulate hyaline droplets formed from reabsorbed plasma proteins, and hyaline casts composed of Tamm-Horsfall protein may appear in urine. Hyaline membranes, another form of hyaline material, line alveoli in diffuse alveolar damage and are a hallmark of acute respiratory distress syndrome.

Causes of hyalos deposition include chronic hypertension, diabetes, aging, and other conditions causing vascular or epithelial injury. The presence of hyaline material is usually a nonspecific indicator of tissue injury or aging rather than a disease in itself, though it can contribute to organ dysfunction when extensive.

See also: hyaline arteriolosclerosis, hyaline membranes, hyaline casts.