disorders of cornification Flashcards
ichthyosis vulgaris defect
profilaggrin synthesis defect –> decreased profilaggrin in keratinocytes –> retention hyperkeratosis
decreased filaggrin –> transepidermal H2O loss
ichthyosis vulgaris presentation (4) and histo
1) fine white translucent scale sparing flexures
2) hyperlinear palms
3) KP
4) atopic triad with hayfever and asthma
histo: absent granular layer
x-linked ichthyosis defect
steroid sulfatase deficiency –> accumulation cholesterol-3 sulfate in epidermis –> inhibition transglutaminase 1
x-linked ichthyosis presentation (5) and histo
1) halted labor
2) 2-6 wks old mild erythrodermal and exfoliation –> brown adherent scale
3) preauricular involvement, dirty neck
4) corneal opacities
5) cryptochidism
histo: normal - thickened granular layer
epidermolytic hyperkeratosis psuedonyms
bullous congenital ichthyosiform erythroderma
bullous ichthyosis
epidermolytic hyperkeratosis defect
50% AD & sporadic
keratins K1 and K10 on genes 12q and 17q
(only K1=PPK, only K10=spares palms/soles)
clumped keratin filaments on electron microscopy at 20-22 wks GA
epidermolytic hyperkeratosis
epidermolytic hyperkeratosis presentation (4)
1) newborn w/ widespread bullae & erythroderma
2) hyperkeratosis with dark warty scales in flexures
3) PPK
4) secondary infections (staph) & foul odor
scales shed full-thickness SC –> denuded base
lamellar ichthyosis defect
AR transglutaminase 1 (also ABCA12, CYP4F, NAP14)
–> defective cross-linking of involucrin –> defective cornification & desquamation
lamellar ichthyosis precentation (5) and findings on EM
1) collodion baby
2) large dark plate-like scale increased in flexures
3) scarring alopecia
4) hypohydrosis
5) PPK & nail dystrophy
EM: lipid vacuoles in corneocytes
congenital ichthyosiform erythroderma defect
AR heterogeneous (ALOX12 B gene, ALOXE3, transglutaminase 1, ichthyin, NEPL4, ABCA12, PNPLA1) --> accelerated epidermal cell turnover rate
congenital ichthyosiform erythroderma presentation (5)
1) collodion baby
2) generalized erythroderma with fine white scale involving flexures
3) cicatricial alopecia
4) ectropion
5) heat intolerance
harlequin fetus defect
AR heterogeneous (ABCA12) also de novo deletion 18q21 defective keratinization & hyperkeratosis lipid accumulation in stratum corneum defective profilaggrin
harlequin fetus presentation
1) collodion baby w/ ectropion & eclabium
2) hyperkeratotic plates w/ deep fissures
sjögren-larsson syndrome defect
AR fatty aldehyde dehydrogenase (FALDH)
defective conversion fatty alcohol to fatty acid –> defective catabolism phospholipids and sphingolipids –> fatty alcohol, fatty aldehyde, and leukotriene B4 build up
sjögren-larsson syndrome presentation (4S’s + 3)
4 S’s in name
Stupid
Spastic/speech problems
Scissor gait
Seizures
ö = glistening perimacular white dots (retinal pigment degeneration) = pathognomonic
also itchy ichthyosis and dental dysplasia
refsum syndrome defect
AR PAHX on ch10p and PEX7 on ch6q
Ref them up - pahx and pex
refsum syndrome presentation (6)
RAPID retinitis pigmentosa ataxia peripheral neuropathy ichthyosis deafness (sensorineural)
You get into a phyt (phytanic acid) when you Ref them up, Pahx and Pexz to the heart (arrhythmia & heart block) and brain and pour salt & pepper into the eyes
refsum syndrome lab abnormality and treatment
increased serum phytanic acid
lipid-filled vacuoles in basal keratinocytes
dietary restriction of green veggies, dairy, ruminant fats
conradi-hünermann syndrome defect
XLD emopamil-binding protein on chXp11
conradi-hünermann syndrome presentation (4)
lethal in males
1) patchy alopecia
2) short stature
3) chondrodysplasia punctata (ü) & asymmetric limb shortening
4) ichthyosiform erythroderma in blaschko’s lines –> follicular atrophoderma & hyperpigmentation
CHILD syndrome pneumonic
Congenital Hemidysplasia with Ichthyosiform erythroderma and Limb Defects
CHILD syndrome defect
XLD NSDHL gene on Xq28
(DHL delivery delivering a CHILD)
–> defective cholesterol biosythesis
CHILD syndrome presentation (3)
1) ichthyosiform erythroderma & alopecia
2) ipsilateral limb deformity & organ hypoplasia
3) stippled epiphyses
netherton syndrome pseudonym
ichthyosis linearis circumflexa
netherton syndrome defect
AR SPINK5 gene on ch5q32
gene encodes LEKT1 (serine protease inhibitor) - important for down-regulating inflammation, linked to atopy
netherton syndrome presentation (4)
1) generalized erythema & hypernatremia at birth
2) ichthyosis linearis circumflexa with double edged scale
3) trichorrhexis invaginata (bamboo hairs)
4) atopy and seborrheic-like scale
netherton syndrome associated risks (4)
1) anaphylactic rxn to foods
2) HPV
3) SCC
4) increased risk infections
erythrokeratoderma variabilis defect
AD GJB3 or GJB4 gene
encodes for connexin 31 and 30.3
erythrokeratoderma variabilis pseudonym
mendes da costa syndrome
erythrokeratoderma variabilis presentation (2)
1) migratory erythematous patches
2) fixed focal hyperkeratotic plaques
KID syndrome pneumonic
Keratitis-Ichthyosis-Deafness syndrome
KID syndrome defect
AD and AR (90% sporadic)
GJB2 gene encodes connexin 26
(also GJB6 - connexin 30)
KID syndrome presentation (6+risks)
1) erythroderma at birth
2) erythematous keratotic plaques
3) stippled palmoplantar keratoderma
4) non-scarring alopecia
5) photophobia –> vascularized keratitis –> blindness
6) sensorineural deafness
also bacterial/fungal infections, SCC, pilar tumors/cysts
diffuse palmoplantar keratoderma defect
AD
Vörner = keratin genes 9 and 1 (german)
Unna-Thost: keratin gene 1
diffuse palmoplantar keratoderma presentation (4)
birth to 1 yr
1) hyperkeratosis palms and soles w/ white-yellow hue & erythematous border and desquamation
2) no transgrediens (do not cross Weber’s line)
3) hyperhidrosis +/- bromhidrosis
4) painful fissuring
