SKIN 2 Flashcards
- part of the epidermis that extends downward going to the dermis
Rete ridges
part of the dermis that
extends upward to the epidermis
Dermal papillae/papilla
• Composed of either 4 or 5 layers depending on the
location
• For areas with thick skin, composed of 5 layers. For
thin skin, 4 layers
Epidermis
Single layer of cuboidal cells which are mitotically
active which actively divides and migrate toward the
upper surfaces to give rise to keratinocytes
Stratum Basale or Stratum Germinativum
• Spinous layer
• Composed of more mature keratinocytes
• Keratinocytes- polygonal shaped cells in the
epidermis and attached to one another through
intercellular bridges called DESMOSOMES
Stratum Spinosum
• Also made up with keratinocytes but with
characteristic cytoplasmic granules called
KERATOHYALINE GRANULES
Stratum Granulosum
• 4th layer, that is present only on thick skin including
the palms and soles
• Made up of clear cells, flattened keratinocytes
Stratum Lucidum
• The outermost layer, cornified or horny-cell layer
• Composed of dead skin cells which are usually
sloughed off
Stratum Corneum
• Thickening of the spinous layer
Acanthosis
• Separation of keratinocytes because of disruption of
desmosomes (or what we call the intercellular bridges)
• Clinical manifestation: BLISTERS
Acantholysis
• Thickening of cornified layer or stratum corneum
Hyperkeratosis
• Vacuolar change of the basal layer with lymphocytic infiltrate at the DEJ
Interface Dermatitis:
• Separation of spinous layer because of increased
(edema) fluid in epidermis
Spongiosis
There is a defective desquamation resulting to
accumulation of dead skin cells or dead keratinocytes
with in the stratum corneum
Ichthyosis
Four types of Ichthyosis
Congenital Ichthyosiform Erythroderma
Lamellar Ichthyosis
X-linked Ichthyosis
Ichthyosis Vulgaris
Main pathology for Ichthyosis
HYPERKERATOSIS
ACUTE INFLAMMATORY DERMATOSES
Urticaria
Acute eczematous dermatitis
Erythema multiforme
ACUTE INFLAMMATORY DERMATOSES common microscopic findings
neutrophilic
infiltration and edema
- A.K.A. Hives/wheals (when confluent)
- (disorder of a) Localized mast cell degranulation
- (results in) Increased vascular permeability
Urticaria
Individual lesions develop and fade within hours
(usually less than 24 hours), and episodes may last for days or persist for months
Urticaria
Urticaria main pathology:
Antigen-induced release of vasoactive mediators from mast cells
• Types of Mechanism for Urticaria:
o Mast Cell-dependent, (IgE)-Dependent
o Mast Cell-dependent, (IgE)-independent
o Mast cell-independent, (IgE)-independent
Type I hypersensitivity
o Mast Cell-dependent, (IgE)-Dependent
§ Direct cell § From direct effect of the substances that we have contact with § Instead of the antigen being presented with the IgE, this type of mechanism DOES NOT INVOLVE IgE
o Mast Cell-dependent, (IgE)-independent
Mast Cell-dependent, (IgE)-independent examples
Opiate Analgesics and some
antibiotics
§ Local Factors
§ Rare, less well-understood
§ Hypothesis: due to the release of local factors one example is exposure to ASPIRIN but he
mechanism of Aspirin-induced urticarial is not very much understood
o Mast cell-independent, (IgE)-independent
gross appearance of urticaria
- Erythematous, edematous plaques
* Annular, linear or arciform
microscopic appearance of urticaria
• Perivenular infiltrate consisting of mononuclear cells (lymphocytes surrounds the vessels) and rare PMNs
• Eos (eosinophil) may also be present
• Aside from the epidermal involvement, Perivascular
Edema
Urticaria Treatment
- Take oral anti-histamines
- Localized: topical steroids
- Sever and more wide spread: IV anti-histamines and corticosteroids
meaning “to boil over,”
eczema
Acute Eczematous Dermatitis is Group of disorders that presents with _________
PATTERN
SPONGIOTIC
AED main/common histologic appearance
Edema
Types of dermatitis
o Allergic contact dermatitis o Atopic dermatitis o Drug related eczematous dermatitis o Photo eczematous dermatitis o Primary irritant dermatitis
AED causes:
o disease resulting from external application
of an antigen (e.g., poison ivy)
o reaction to an internal circulating antigen
(which may be derived from ingested food
or a drug).
AED Treatment:
o search for offending substances that can be
removed from the environment
o topical steroids (corticosteroids) and
moisturizers can be used to block the inflammatory response
AED hypersensitivity Type?
IV
Focally,
crusted, thickened, plaques and papules with some
areas of erythema and redness. The crusts are
dried up yellowish exudates
atopic dermatitis
Gross morpho AED
Red, papulovesicular, crusted
Characterized by pruritic,
edematous, oozing plaques that often contain small
and large blisters (vesicles and bullae) that are prone to bacterial superinfection, which produces a yellow crust (impetiginization)
Allergic contact dermatitis
o Characterizes acute eczematous dermatitis
o Edema seeps into the intercellular spaces
of the epidermis, splaying apart
keratinocytes, particularly in the stratum
spinosum
spongiosis
Initial manifestation of AED
papillary dermal edema and
mast cell degranulation manifested by whites’
spaces with concomitant superficial,perivascular, lymphocytic infiltrate
perivascular infiltrates that often contain eosinophils in the superficial and deep dermis
Certain ingested drugs
produce a mononuclear inflammatory reaction
without eosinophils that
preferentially affects the superficial dermis.
Contact antigens
o body surface involved is <10% o febrile form; extensive involvement of the skin o often seen in children o skin, lips and oral mucosa, conjunctiva, urethra, and genital and perianal areas o Loss of skin integrity -> Secondary infection -> sepsis
Steven-Johnson Syndrome
o body surface area involved is >30%
o diffuse necrosis and sloughing of cutaneous and mucosal epithelial surfaces
Toxic Epidermal Necrolysis
between 10% to 30%
SJS-TEN overlap
ERYTHEMA MULTIFORME • Keratinocyte injury mediated by skin-homing CD8+ cytotoxic T lymphocytes o \_\_\_\_\_\_\_ - central portion of the lesions o \_\_\_\_\_\_\_\_\_\_\_ - peripheral portions
CD8+ cytotoxic T cells; CD4+ helper T cells and Langerhans cells
- Macules, papules, vesicles, bullae
* Characteristic targetoid (target-like) lesions
Erythema multiforme
micro morpho Erythema multiforme
• Interface dermatitis
CHRONIC INFLAMMATORY DERMATOSES
Psoriasis
Seborrheic dermatitis
Lichen planus
• Chronic inflammation that appears to have an
autoimmune basis.
• Koebner phenomenon
• Auspitz sign
Psoriasis
Psoriasis pathogenesis
- CD4+Th1 and Th17 cells
* CD8+ cytotoxic effector T cells
most frequently affects the skin of the elbows, knees, scalp, lumbosacral areas,
intergluteal cleft, and glans penis.
psoriasis
is defined if one person to
develop psoriasis and experience local trauma they can trigger the formation of your plaques and papules.
Koebner Phenomenon
