Pathophys/Path 5 Flashcards
Embryology of Skin
gastrulation: divide into 3 layers
- ectoderm goes to ectoderm and neuroectoderm
- mesoderm
- endoderm
Epidermis
formed by epidermis
-stratum baslaem
-stratum spinulosum
-stratum granulosum
stratum lucidum
stratum corneum
- defect lead to ectodermal dysplasias
week 6-bilayered epidermis (periderm, basal layer)
week 8-stratification begins (intermediate, basal)
Ectodermal Dysplasias
defects in hair, teeth, bone, skin
Skin by mid Trimester
- terminally differentiated epidermal layers similar to adult skin
- filaggrin expressed and cornified cell envelope formed
- defects lead to ichthyoses
- Ichythosis vulgaris due to filaggrin mutation
Cell lines in epidermis
- melanocytes
- langerhans
- merkle
Melanocyte embryology
Originate in the neural crest
- migrate to ear,eye,skin,leptomeninges
- origin/migration/survival defect leads to patches lead depigmentation where no migration took place
Piebaldism
-defective melanocyte mutation leads to patches of depigmentation
Waardenberg syndrome
- defective survival of melanocytes leads to patches of depigmentation
- enteric ganglion cells also effected (heart/other problems)
Hermansky Pudlak and Chediak Higashi Syndrome
- ineffective transfer of melanosomes to keratinocytes lead to pifmentary dilution (silver hue)
- may affect other cells where lysosomal trafficking is important (neutrophils, neurons, platelets)
Alminism
- ineffective melanin production
- melanocytes are present, but no melanin
- genes lead to diff phenotypes
Mosaicism
- different gene populations in one individual
- melanocytes develop along lines of Blaschko
- pigmentary mosaicism seen as linear streaks or whorls
- X-linked conditions often follow lines of blaschko due to lyonizatioin
Dermis embryology
- derived from both ectoderm and mesoderm
- by 12 weeks, fully functional EGA (dermal-epidermal junction)
- barrier function of skin not fully developed until 3 weeks after birth
Neonatal Dermatology
- surface area to weight ratio is 5 times that of adults
- increased percutaneous absorption of topical medicines
- premature infants have increased transepidermal water loss (TEWL)
Vernix Caseosa
- protective membrane present at birth
- mechanical barrier in utero
- composed of epithelial cells, sebaceous secretions, and shed lanugo hair
Cutis Marmorata
- accentuated with temperature decrease
- resolves with re-warming
Erythema Toxicum Neonatorum
- tiny pustules with wheel, evervescent
- benign
- up to 50% of infants
- resolve spontaneously
Miliaria
- due to occlusion of eccrine glands at different levels
- miliaria cystallina
- miliaria rubra
Neonatal Acne
“Neonatla Cephalic Pustulosis”
- primary lesion is pustule not comodone
- due to maternal hormones
- Maallessezia may also play role
- resolves spontaniously
Transient Neonatla Pustular Melanosis
-leaves darker spots
-more common in AA infants
-resolves spontaneously
-
Seborrheic Dermatitis
cradle cap
self-limited
Diaper Dermatitis
- wide differentiation
- several common causes: irritant, candidia
other: seborrhic
or: seborrheic dermatitis, psoriasis, allergic contact, nutritional deficiencies, langerhans cell histiocytosis, jacquet’s dermatitis
Atopic Dermatitis
-up to 20% in US
-60% will present within first year of life
-85% by age 5
-can be associated with asthma and allergic rhinitis
“atopic march”-eczema, asthma, rhinitis
Cause of atopic dermatitis
filaggrin mutatuins -know to cause ichthyosis vulgaris
-strongly associated with AD, linked with early onset
Pathogenesis of Atopic Dermatits
- barrier dysfunction leads to exposure to allergens
- secondary immune dysregulation due to increased allergen exposure
Criterial of Dermatitis
-Pruritus in past 12 months
plus 3 of following:
*history of dry skin in last year *personal/family allergic rhinitis history *onset before 2 *history of skin crease involvement *visible flexural dermatitis (<4 cheeks, forehead, extensor)
Atopic dermatitis: infantile phase
cheeks, forehead, scalp, extensor
- spares diaper are
- intense pruritis,erythema, oozing
Atopic Dermatitis: childhood phase
favors flexor surfaces, wrists, ankles, neck
-lichenification common
AD complications
Infection-staph (90%)
- eczema herpeticum-explosive eruption of herpes simplex
- molluscum contagiosum-more in AD
- behavioral- increased ADHD