Skin DEVO and associated Dz Flashcards
epidermis and epidermal derivatives originate from…
surface ectoderm
melanocytes and merkel cells are derived from….
neural crest
what type of signaling is essential in skin devo?
ectoderm-mesenchyme
piebaldism is d/t…
absence of melanocytes, d/t mut in KIT proto-oncogene
Dermis is derived from…
regional mesenchyme
port-wine stains in the V1 dermatome from sturge-weber syndrome are associated with what two things?
glaucoma and seizures
term for sloughed off periderm cells and sebum?
vernix caseosa
- protective
- facilitates childbirth d/t lubricating nature
nails are derived from…
epidermal thickenings at the tips of digits
describe the epidermis in weeks 4-8
2 layers:
- periderm
- basal layer
describe the epidermis in week 11
3 layers:
- mitosis from basal layer –> intermediate layer
- embryo is now surrounded by amnion, which is becoming more complex
describe the epidermis at 11-21 wks
definitive skin layers (granulosum, spinosum, etc.)
- epidermal ridges extend into the forming dermis
- sebaceous glands excrete vernix caseosa
- kidneys are functioning, causing amniotic fluid to be more caustic
- langerhans, merkels, and melanocytes present
is piebaldism progressive?
no
describe the presentation of piebaldism
congenital depigmented patches, often with speckles within
stable, non-progressive
white forelock
do not expand, just grow with child
Waardenburg syndrome is d/t…
multiple gene mut»_space; abn devo of melanocytes
what is the inheritance pattern of waardenburg syndrome?
AD, rare
List the 4 common features of Waardenburg syndrome
Achromia
Deafness
Heterochromia irides
Dystopia canthorum (wide distance between eyes, not pupils)
how do dermal vascular plexuses form?
angiogenesis from nearby vessels
term for a capillary malformation present at birth that darkens and thickens over time
port wine stain
if a port-wine stain is present in the V1 dermatome, where might it extend?
ocular conjunctiva
if a port-wine stain is present in the V3 dermatome, where might it extend?
oral mucosa
what is the most common vascular tumor/birthmark?
infantile hemangioma
describe the growth cycle of infantile hemangiomas:
birth - appear as a white flat patch with find pink-red vessels
3-9 mos. - growth phase
Then slow involution, and resolution with residual textural changes and telangiectasia)
what does PHACE stand for?
Posterior fossa abnormalities Hemangioma Arterial anomalies Cardiac anomalies Eye anomalies Sternal clefting/supraumbilical raphe (midline fusion defects)
what type of secretion from eccrine glands?
merocrine
a set of >150 rare syndromes d/t alterations in 2+ structures derived from embryonic ectoderm
ectodermal dysplasias
what is the inheritance pattern of hypohydrotic ectodermal dysplasia
XR
- EA1 mut
- EA1R mut
- EAR associated death domain mut
pt presents with impaired ability to sweat, and overheating…
hypohydrotic ectodermal dysplasia
how do you care for a patient with hypohydrotic ectodermal dysplasia?
avoid overheating, consult dentistry (peg teeth), recommend support groups
the dermis-forming mesenchyme on the ventrolateral body is derived from…
somatic mesoderm
the dermis-forming mesenchyme on the dorsum of the body is derived from….
dermatomes
describe the epidermis at week 21
periderm and stratum corneum coexist; periderm disappears before birth
origin of sebaceous glands?
buds from epithelial root sheath of hair follicle
origin of eccrine sweat glands?
epidermal placode that becomes a bud which extends into the dermis
structure of sebaceous glands?
branched
structure of eccrine sweat glands?
buds elongate and coil
length of sebaceous duct?
short
length of eccrine sweat gland duct?
long
when do eccrine sweat glands begin to function?
shortly after birth
when do apocrine sweat glands begin to secrete?
after puberty
when does hair begin to form?
early fetal period
when do nails begin to form? finish?
wk 10/14 (UL/LL), finished at 32/36 wks
describe the steps of hair formation
placode > proliferation > bud > extends into dermis > distal end expands to form hair bulb > extension of dermis into base of bulb form dermal papilla
by examining the fingernails of a newborn, how could you determine if this infant is premature?
nails have not reached tips of digits
how are hair and skin pigmented?
wk 6-7 melanoblasts appear in forming dermis, migrate to epidermal-dermal border (and hair follicles) where they differentiate into melanocytes
- melanin granules are transfered to cells in base of epidermis just before birth
what is the precursor of errector pili muscles?
dermal mesenchyme adjacent to the forming hair follicle
what would you suspect if you delivered a baby with gray hair?
Albinism (AR trait)
albinism is d/t
lack of tyrosinase
what are the general characteristics and probable causes of ICHTHYOSIS
group of skin disorders d/t excess keratinization
- skin is dry and scaly
what are the general characteristics and probable causes of LAMELLAR ICHTHYOSIS
infants have skin composed of large plate-like scales
- cornified layer is unable to shed properly
- d/t defect in transglutaminase 1 gene
what are the general characteristics and probable causes of COLLODIN BABY
a form of ichthyosis
- infant covered in thick, taut membrane of keratin (wrapped in parchment)
- eventually membrane cracks and sloughs in sheets (weeks)
- exposed skin may be normal
what are the general characteristics and probable causes of HARLEQUIN ICHTHYOSIS
most severe ichthyosis
- massive armor-like plaques
- cracks appear after birth (infection, dehydration, etc.)
- cannot open eyes/mouth > trouble breathing
- most infants die w/in a couple weeks after birth
- now treated with isotretinoin with increased survival
what are the general characteristics and probable causes of CONGENITAL ALOPECIA
absence or loss of scalp hair
- d/t failure of hair follicles to develop (or production of poor-quality hair)
- may be associated with other skin anomalies
what are the general characteristics and probable causes of HEMANGIOMA
tumor of endothelial cells
- rubbery, red-purple, raised
- face, scalp, neck
what are the general characteristics and probable causes of CAPILLARY MALFORMATION
flat lesions of dilated capillaries in superficial dermis
- aka port wine stain/birthmarks
- associated with increased levels of VEGF and VEGF-R2
- persist through life and grow proportionately
what are the general characteristics and probable causes of OCULAR ALBINISM
- albinism of eyes
- XR
what are the general characteristics and probable causes of OCULOCUTANEOUS ALBINISM
group of inherited disorders w/ absent pigmentation in skin, hair and iris
- d/t genetic defect in tyrosine
- defining characteristic is presence of vision problems d/t abn retinal devo and optic nerve abnormalities
what are the general characteristics and probable causes of CONGENITAL ECTODERMAL DYSPLASIA
heterogeneous group of inherited (XR) disorders that have primary defects in 2+ tissues derived from epidermis or oral ectoderm
- hair, eccrine glands, teeth and nails
