Nail shedding (onychomadesis) is a progression of profound Beau’s lines. It describes the detachment of the nail plate from the proximal nail fold and is due to a severe insult that products a complete arrest of nail matrix activity. The causes of onychomadesis include mechanical trauma, eczema and chronic paronychia.
Retrospectively, it can indicate a previous bout of hand-foot-mouth disease, scarlet fever, Kawasaki disease, it may also appear in the setting of pemphigus vulgaris or Stevens-Johnson syndrome.
Local dermatoses such as the bullous disorders and paronychia may cause nail loss. Generalized dermatoses may be manifest, for example toxic epidermal necrolysis (TEN) and severe/rapid onset of pustular psoriasis. Scarring of the nail unit is seen in lichen planus and following TEN, which may both provoke nail loss.
Temporary loss has also been described due to retinoids, and to large doses of cloxacillin and cephaloridine during the treatment of two anephric patients. Onychoptosis defluvium or alopecia unguium describes atraumatic, familial, non‐inflammatory nail loss. It may be periodic and associated with dental amelogenesis imperfecta. Nail shedding can be part of an inherited structural defect, most obviously in epidermolysis bullosa.
脱甲病是指甲板从近端甲褶皱处脱落，这是由于严重损伤导致指甲基质活动完全停止。物理损伤、湿疹或慢性甲沟炎可造成此症。它可以表明以前的手足口病，猩红热，川崎病，也可能出现在寻常型天疱疮或史蒂文斯 – 约翰逊综合征的情况下。
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