Nail Involvement in Epidermolysis Bullosa




Nail abnormalities are a common feature in most subtypes of epidermolysis bullosa (EB), and they recently have been included among the criteria for scoring EB severity. Trauma undoubtedly contributes to the development of nail dystrophy, and for this reason the great toenails often are affected more severely. The nail abnormalities may be the first or the only symptom of EB. Nail abnormalities observed in EB are not specific or pathognomonic, as they result from nail bed and matrix scarring. The spectrum of clinical severity is large, and nail abnormalities may cause severe disability or just be a mild cosmetic problem. This article reviews the nail abnormalities observed in EB.


Although the anatomy of the nail apparatus is different from that of the skin, the antigenic expression of basement membrane zone (BMZ) components in the normal matrix, nail bed, proximal nail fold, and hyponychium is similar to that of normal skin. In addition, there are no differences in the antigenic composition of the BMZ between the different portions of the nail matrix. Nail expression of all the target antigens found in the normal nonappendage basement membrane explains why nail involvement is a feature of most epidermolysis bullosa (EB) subtypes.


Even though the absence or presence of nail changes at birth should not be used as absolute criteria for differential diagnosis between different subtypes of EB, nail involvement recently has been included among the criteria for scoring EB severity, as early nail dystrophy and loss are correlated with disease severity and progression, particularly in junctional epidermolysis bullosa (JEB) and recessive dystrophic epidermolysis bullosa (RDEB).


Trauma undoubtedly contributes to the development of nail dystrophy, and for this reason, the great toenails more often are affected severely.


The nail abnormalities may be the first or the only symptom of EB. In fact they may precede the development of skin blistering as in the late-onset JEB ( Fig. 1 ) and pretibial DEB, or be an isolated finding as reported in some families with dominant dystrophic EB (DDEB) ( Figs. 2 and 3 ).




Fig. 1


Late-onset JEB: thickened toenails; in the fourth right toe there is loss of the nail and granulomatous tissue.



Fig. 2


Nail dystrophy of the first left toenail in child with dominant dystrophic EB nails only.



Fig. 3


Toenail dystrophy in the mother of the child from Fig. 2 .


Nail involvement is uncommon in localized EB simplex (EBS) and is not a feature of EBS migratory circinate or EBS with pyloric atresia ( Table 1 ).



Table 1

Classification of EB and the nail involvement in the different subtypes of EB

































































































































Major Type of EB Subtypes Frequency of Nail Involvement Nail Signs
EBS
(simplex)
EBS superficialis AD 70% Dystrophic nails
Lethal acantholytic EBS AR 100% Nail loss
Plakophilin deficiency AR 100% Thickened dystrophic nail
EBS localized AD Uncommon Blistering may cause onycholysis and onychomadesis, with normal regrowth or thickened dystrophic nails
Dowling-Meara AD >75% Onychomadesis, pachyonychia, onychogryphosis, pincer nails or absent nails
EBS other generalized AD (previously called Koebner) 14% Onychomadesis with normal regrowth, pachyonychia, thickened great toenail
AR EBS Hyperkeratotic nails, horizontal ridging, anonychia
EBS-Ogna AD Onychogryphosis
EBS migratory circinate Absent None
EBS with mottled pigmentation Uncommon Dystrophic nails, small toenail
EBS with muscular dystrophy 50% Onychomadesis, pachyonychia, onychogryphosis, pincer nails, anonychia
EBS with pyloric atresia Absent None
JEB Herlitz AR >75% Pachyonychia, exuberant granulation tissue, nail erosion, anonychia
Non-Herlitz AR (generalized and localized) >75% Anonychia, dystrophic nails
With pyloric atresia AR Nail thinning and atrophy or absent nails
Inversa JEB >50% Dystrophic or absent nails
Late-onset JEB Onycholysis, nail loss, Beau’s lines
LOC syndrome 100% Nail thickening, nail erosions with granulation tissue, anonychia
DEB
(dystrophic EB)
DDEB generalized >75% Nail thickening, onychogryphosis, anonychia, pseudosyndactyly
RDEB severe generalized >75% Anonychia, pseudosyndactyly
RDEB generalized other >75% Dystrophic or absent nails
Acral DDEB and RDEB >75% Nail thickening anonychia
Pretibial DDEB and RDEB, >75% Nail thickening
Pruriginous DEB, AD or AR >75% Nail thickening, anonychia
DDEB nails only 100% Pachyonychia, thickened dystrophic nails anonychia
DEB-BDN 25 – 50% Nail thickening, anonychia pseudosyndactyly
RDEB inversa >75% Nail thickening
RDEB centripetalis >75% Dystrophic or absent nails
Kindler syndrome AR Nail dystrophy, parrot beak nail deformity, absent nails

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Feb 12, 2018 | Posted by in Dermatology | Comments Off on Nail Involvement in Epidermolysis Bullosa
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