Desquamation, or peeling skin, is the shedding of dead cells from the outermost layer of skin.
The term is .
Physiologic desquamation
Keratinocytes are the predominant cells of the epidermis, the outermost layer of the skin. Living keratinocytes reside in the basal, spinous, or granular layers of the epidermis. The outermost layer of the epidermis is called the stratum corneum and it is composed of terminally differentiated keratinocytes called the corneocytes. In the absence of disease, desquamation occurs when corneocytes are individually shed unnoticeably from the surface of the skin. Typically the time it takes for a corneocyte to be formed and then shed is about 14 weeks but this time can vary depending on the anatomical location that the skin is covering. For example, desquamation occurs more slowly at acral (palm and sole) surfaces and more rapidly where the skin is thin, such as the eyelids. Normal desquamation can be visualized by immersing skin in warm or hot water; inducing the outermost layer of corneocytes to shed (such as is the case after a hot shower or bath).
Corneocytes are held together by corneodesmosomes. In order for desquamation to occur these corneodesmosome connections must be degraded. Kallikreins are serine proteases; packaged within the lamellar bodies and released into the intercellular space between the keratinocytes as they transition into becoming corneocytes. can cause severe desquamation; so can mercury poisoning. Other serious skin diseases involving extreme desquamation include Stevens–Johnson syndrome and toxic epidermal necrolysis (TEN). Radiation can cause dry or moist desquamation. Desquamation is also abnormal in patients with immune-mediated skin diseases such as psoriasis and atopic dermatitis. The anatomy of the human eye makes desquamation of the lens impossible.
See also
- Desquamative gingivitis
- Exfoliation joint
- Moist desquamation
- Pityriasis—flaking of the skin
- Spalling
- Sunburn