chapter
Keratinization^29
(Cornification)
Disorders
DEFINITION/OVERVIEW
Keratinization is the process by which the basal keratinocyte differentiates into the
highly specialized corneocyte of the stratum corneum.
Keratinization disorders occur when there is an inability to form a normal stratum
corneum (outermost layer of the epidermis).
Alterations in the formation, maturation, and desquamation of the epidermis result
in visible abnormalities in the skin.
Commonly referred to asseborrhea, a nonspecific term describing excessive scaling
and crusting, with or without greasiness.
Overall increased shedding (desquamation), as well as decreased shedding of indi-
vidual epidermal cells, results in the clinical presentation of cutaneous scaling.
The hydrophobic barrier of the stratum corneum is a fragile balance of phospholipid-
derived free fatty acids, cholesterol, and ceramides; this outermost layer (epidermal
lipid barrier) serves as the primary barrier between the body and the surrounding
environment.Structural or physiologic abnormalities to the epidermal lipid barrier may cause
excessive greasiness or dryness of the skin and encourage development of secondary
infection.Keratinization disorders may be acquired (secondary to alterations induced by aller-
gic skin disease, ectoparasitism, and/or endocrine/metabolic diseases) or inherited
(ichthyotic and nonichthyotic).Treatment includes correction of the underlying etiology (if not primary), control
of secondary infection, reduction in epidermal turnover, reduction of inflammation,
restoration of epidermal barrier function, and removal of excessive epidermal accu-
mulations.ETIOLOGY/PATHOPHYSIOLOGY
Keratinization disorders include a large number of syndromes and encompass der-
matoses caused by a disruption in the normal and orderly process by which ker-
atinocytes divide in the basal cell layer, mature, die, and are ultimately shed.Blackwell’s Five-Minute Veterinary Consult Clinical Companion: Small Animal Dermatology, Third Edition.
Karen Helton Rhodes and Alexander H. Werner.
©2018 John Wiley & Sons, Inc. Published 2018 by John Wiley & Sons, Inc.
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