47 - The Ichthyosis Flashcards
Parental consanguinity may suggest _____ inheritance
Autosomal recessive
Chorionic villous sampling performed in the
1st trimester
Amniocentesis performed in the
2nd trimester
Symptoms of salicylic acid intoxication
Nausea
Tinnitus
Dyspnea
Hallucinations
Most common ichthyosis
Ichthyosis vulgaris
Gene mutation and protein: ichthyosis vulgaris
FLG
Filaggrin
Scale is usually most prominent on the extensor surfaces of the extremities, with flexural sparing
Diaper area tends to be spared
Ichthyosis vulgaris
Mode of inheritance: ichthyosis vulgaris
Autosomal semidominant
Associated findings include hyperlinear palms, palmar/plantar thickening, keratosis pilaris, atopy
Ichthyosis vulgaris
Gene mutation and protein: X-linked recessive ichthyosis
STS
Steroid sulfatase
Scaling is most prominent on the extensor surfaces, with significant involvement of the flexural areas
Comma-shaped corneal opacities
Increased risk of cryptorchidism and testicular cancer
X-linked recessive ichthyosis
Steroid sulfatase hydrolyzes sulfate esters, which include
Cholesterol sulfate
Sulfated steroid hormones
Absence of steroid sulfatase enzyme in the fetal placenta leads to
Low maternal urinary estrogens
Failure of labor to initiate or progress normally
Majority of maternal urinary estrogens are derived from the
Fetal adrenal glands
During the first _____ of life, the collodion membrane breaks up and peels off
2 weeks
Types of autosomal recessive congenital ichthyosis
- Lamellar ichthyosis
- Congenital ichthyosiform erythroderma
- Harlequin ichthyosis
- Netherton syndrome
ARCI:
Large, dark, platelike scales
Infants may be red at birth, adults have little to no erythroderma
Ectropion, eclabium
Scarring alopecia most prominent at the periphery
Lamellar ichthyosis
ARCI:
Generalized redness and fine, white scales
Little to no ectropion, eclabium or alopecia
Congenital ichthyosiform erythroderma
Gene mutation and protein: lamellar ichthyosis
TGM1
Transglutaminase 1
Bathing suit ichthyosis is a type of
Lamellar ichthyosis
Thick, shiny plates of stratum corneum separated by deep, red fissures that tend to form geometric patterns
Poorly developed or absent ears
Marked ectropion and eclabium
Fingertips are tapered with hyperconvexity of the nails
Harlequin ichthyosis
Ichthyosis linearis circumflexa
Trichorrhexis invaginata
Atopy
Netherton syndrome
Polycyclic, serpiginous, migratory, double-edged scale at the margins of erythematous plaques
Ichthyosis linearis circumflexa
Distal hair segment is telescoped into the proximal one
Also known as “bamboo hair”
Trichorrhexis invaginata
Trichorrhexis invaginata is caused by abnormal cornification of the
Inner root sheath
Trichorrhexis invaginata is more commonly observed on
Eyebrow hair
Gene mutation and protein: congenital ichthyosiform erythroderma
ALOXE3 - lipoxygenase 3
ALOX12B - 12(R)-lipoxygenase E3
Gene mutation and protein: Harlequin ichthyosis
ABCA12 Adenosine triphosphate (ATP)-binding cassette (ABC) transporter
Normal lamellar granules are not found
Small vesicles that lack internal structure
No evidence of the lipid lamellar that form between granular and cornified cells
Harlequin ichthyosis
Gene mutation and protein: Netherton syndrome
SPINK5 LEKTI (lymphoepithelial Kazal-type related inhibitor
Topical and systemic retinoids should be avoided in patients with _____ because they can further exacerbate the condition
Netherton syndrome
Types of keratinopathic ichthyosis
- Epidermolytic ichthyosis
- Superficial epidermolytic ichthyosis/ichthyosis bullosa of Siemens
- Ichthyosis hysterix Curth-Macklin
- Annular epidermolytic ichthyosis
- Ichthyosis with confetti
Mode of transmission: epidermolytic ichthyosis
Autosomal dominant
Presents at birth with blistering, redness and peeling
Generalized hyperkeratosis
Characteristic odor, thought to be related to superinfection by mixed flora
Corrugated scale that becomes accentuated in areas of body folds
Epidermolytic ichthyosis
Variant of epidermal nevus caused by a postzygotic spontaneous mutation
Hyperkeratosis alternating with normal skin distributed in streaks along Blaschko lines
Linear ichthyosiform erythroderma
Mode of transmission: superficial epidermolytic ichthyosis
Autosomal dominant
Corrugated hyperkeratosis, particularly over flexural areas
Loss of the uppermost epidermis (predominantly the stratum corneum), yielding a characteristic collarette-like depressed area that has been described as “mauserung” (molting)
Superficial epidermolytic ichthyosis
Gene mutation and protein: superficial epidermolytic ichthyosis
KRT2
Keratin 2
Mode of inheritance: annular epidermolytic ichthyosis
Autosomal dominant
Severe, intermittent scaling and blistering resolves during puberty
Residual, limited plaques with corrugated scale and erythema primary in flexural and intertriginous skin
Widespread, migratory, polycyclic, and annular scaling plaques
Annular epidermolytic ichthyosis
Gene mutation and protein: annular epidermolytic ichthyosis
KRT10, KRT1
Keratins 10 and 1
On electron microscopic examination, clumping of filaments is observed to begin in the first suprabasal layer
Epidermolytic ichthyosis
Congenital erythroderma, malformation of the auricle, tapering of the digits
Palmoplantar keratoderma
Small islands of normal-appearing skin beginning in childhood
Ichthyosis with confetti
Severe palmar/planes involvement implies mutations in
KRT1
Occurs only in the suprabasal epidermis of palmar and plantar skin
KRT9