Derm/Nero Exam Flashcards
What does the neural crest give rise to?
Posterior root ganglia, sensory (CN), autonomic ganglia, adrenal medulla (extension of neural crest cells), melanocytes, pancreatic islets
What is Colchicine?
medication used to treat gout that blocks microtubule development & may cause neural tube defects
What is the alar plate?
part of the neural tube that makes up the posterior portion (sensory, dorsal horn)
What is the basal plate?
part of neural tube that makes up anterior portion (motor, ventral horn)
What are glial blasts?
premature glial cells - astrocytes, epyndymal cells, oligodendrocytes, microglial cells
What day does the neural fold touch?
21
What day does the superior neuropore close?
What condition results if it fails to close?
- Anacephaly
What day does the inferior neuropore close?
30
What does the ectoderm develop into?
Sensory organs, epidermis, nervous system (CNS/PNS).
What does the mesoderm develop into?
Bone, muscle, dermis, urogenital systems, circulatory system.
What does the endoderm develop into?
GI system, liver, pancreas, respiratory system
What is neurulation and when does it occur?
the process of neural tube formation, embryonic stage (2-8 wks)
What develops in the fetal stage?
Polyneuronal development (migration of cells, 50% die, completed by 25th week), and myelination (finished by 3yrs - corticospinal tracts & cortical association fibers)
Causes of closure 1 problems? (spine above the sacrum)
Folic acid deficiency, metabolic teratogens = spina bifida
Closure 2 problems? (superior head)
Maternal hyperthermia, folic acid defic, metabolic teratogens = anencephaly
Closure 3 problems? (face)
usually resistant = mid-facial clefts
Closure 4 problems? (posterior head)
Maternal hyperthermia = cephalocele
Closure 5? (Sacrum)
valproic acid exposure = sacral closure
What are the benign epidermal tumors?
Seborrheic Keratosis, Acanthosis Nigricans, fibroepithelia polyp (skin tag), epidermal inclusion cyst, adnexal tumors: eccrine, apocrine.
*Derived from keratinizing stratified squamous epitheilum
Types of AN?
Benign (80%): autosomal dominant with variable penetrance, a/w obesity or endocrine abnormalities; Malignant: middle aged/older, a/w GI adenocarcinomas
GI adenocarcinomas effect on pigment?
stimulate fibroblasts to lay more keratin down causing increased pigmentation
What is the pathogenesis of AN? What other disorders have the same mutation?
FGFR3 - achondroplasia, thanatophoric dysplasia
Morphology of fibroepithelial polyp? Associated disorders?
Fibrovascular cores, covered by benign squamous epithelium, can undergo ischemic necrosis d/t torsion.
*Diabetes, obesity, intestinal polyps. May be more prominent/numerous in pregnancy
What makes up an epidermal cyst?
Keratin and lipid debris from sebaceous secretion
Morphology of epidermal inclusion cyst
wall resembles nL epidermis, center filled w/ laminated strands of keratin
Morph of pilar or trichilemmal cysts
Wall: resembles follicular epithelium w/o granular cell layer
Center: filled w/ homongenous mixture of keratin & lipid
Morph of dermoid cyst
Wall: similar to epidermal inclusion w/ multiple appendages budding outward (w/I dermal layer)
Morph of steatocystoma simplex
resembles sebaceous gland duct from which numerous compressed sebaceous lobules originate. Different from multiplex: a missense mutation in keratin
Imipuimod
activates immune system by stimulating Toll-like receptors (to destroy cells)
Hallmark of AK?
parakeratosis
Bowen’s disease
SCC in situ, if no invasion through DEJ - sharply defined, red, scaling plaques involving all levels of epidermis
SCC pathogenesis
DNA damage d/t UV = p53 mutation, dampens immune surveillance by langerhan or NK/lymphocytes in dermis, sensed by kinases normally upregulating p53 expressioin, and if mutated, the response cannot occur. A/w immunosuppression (chemo, organ transplant or steroid use). Implication of HPV 5 & 8
BCC facts
Most common invasive cancer, BLUE PALISADING NESTS. immunosuppression or inherited defects in DNA repair may cause (xeroderma pigmentosum). May contain melanin
BCC morphology
resemble nL basal cell layer, arise from epidermis or follicular epithelium. 2 Patterns: multifocal growths (from epidermis), or nodular lesions (grow downwards into dermis)
Gorlin syndrome
nevoid BCC syndrome, dominant:PTCH gene mutation, 2nd nL allele inactivated by UV light. PTCH encodes receptor for sonic hedgehog gene. absence of PTCH causes activation of SMO leading to BCC.
- before age 20
- a/w: medulloblastomas, ovarian fibromas
Ligand independent signal transuction is in which disease?
BCC - mutated PTCH won’t bind to SMO, and SMO will be activated leading to constant proliferation.
Non BCCS pathogenesis
genetic: PTCH or p53 mutation –> xeroderma pigmentosa
Merkels cell carcinoma?
Very malignant & lethal. Connected to nervous system
Acute Dermatoses
Urticaria, eczema, erythema multiforme
Chronic Dermatoses
Psoriasis, seborrheic dermatitis, lichen planus, lupus erthymatosus
Difference between urticaria and angioedema?
Angioedema has deeper edema of dermis and subQ fat
Pathogenesis for urticarial:
- Ag induced release of vasoactive mediators from mast cells through IgE Ab
- ASA can be instigator (AA produce only LKT)
- Complement mediated urticarial: hereditary angioneurotic edema (def of C1 inhibitor)
How does C1 inhibitory deficiency work?
C1–>C1a always activated, causing constant C3a/C5a activation which have receptors on mast cells causing degranulation
What is seen in persistent eczema?
Raised, scaling plaques d/t acanthosis and hyperkeratosis
Hallmark of eczema?
Epidermal spongiosis
Types of dermal melanocytosis
- Mongolian spot
- nevus of Ota and Ito
- melanocytes in dermis that actively synthesize melanin
- blue color (Tyndall effect)
Differences between Ota/Ito?
Ota: CN V1 & V2
Ito: posterior supraclavicular and lateral brachiocutaneous nerves
What cells are important in dermal immunity and repair?
- fibroblasts
- perivascular mast cells
- dendrocytes
How is melanin synthesized?
Tyrosine to DOPA (by tyrosinase), DOPA to melanin
Differences in melanin in AA and whites?
- whites: degraded faster, only in basal layer
- AA: melanosomes present throughout all layers, and are larger with more dendritic processes, can produce more melanin too.
What are Langerhans cells?
Bone marrow derived, epidermal, immigrant cells.
- regulate contact hypersensitivity, allograft rejection & GVH.
- express MHC-1, MHC-2, Fc IgG & IgE
Layers of the dermis
- Papillary: loose CT beneath the epidermis
- Reticular: dense dermal collagen (tougher, deeper)
Onycholysis
Separation of nail plate from nail bed - trauma, infxn, spontaneous
Acanthosis
diffuse epidermal hyperplasia (chronic irritation)
Papillomatosis
Surface elevation caused by hyperplasia & enlargement of contiguous dermal papilla
Acantholysis
Loss of intercellular cohesion btwn keratinocytes (pemphigus vulgaris)
Spongiosis
Intracellular edema of epidermis
Hydropic swelling
Intracellular edema of keratinocytes, seen in viral infxns.
Exocytosis
Infiltration of epidermis by inflammatory cells
Vacuolization
formation of vacuoles w/I or adjacent to cells
Lentiginous
linear pattern of melanocyte proliferation w/I epidermal basal layer
What are basaloid cells?
Nests of tumor cells resembling normal basal cell layer of the epidermis
Bowen’s disease?
In situ carcinomas of skin caused by HPV infection
