Flashcards in Skin Deck (48)
What characteristics are shared by all forms of eczema?
Early stage lesions are red, papulovesicular, oozing, and crusted. Late lesions develop into raised, scaling plaques.
What are the five forms of acute eczematous dermatitis?
1. Allergic contact
2. Atopic - defects in keratinocyte barrier function.
5. Primary irritant
Do most forms of eczema resolve upon removal of the stimulus?
What morphological change is characteristic of acute eczematous dermatitis? Describe it.
Spongiosis: accumulation of edema between keratinocytes --> breaking of desmosomes. There is also lymphocytic infiltrate, mast cell degranulation, and eosinophil infiltrate (eosinophils are mostly seen in drug-induced type)
Allergic contact dermatitis is a type ____ hypersensitivity reaction in which ____ cells migrate to the affected area, and release cytokines to attract more inflammatory cells.
type 4, T cells
What are the clinical features of acute eczematous dermatitis (2)?
1. Lesions are pruritic (itchy), edematous, and oozing, often containing vesicles and bullae.
2. Persistent stimulation --> scaly lesions (hyperkeratosis), epidermis thickens (acanthosis)
Describe the stages of eczema development.
1. Initial dermal edema and perivascular infiltration by inflammatory cells.
2. 24-48 hours - epidermal spongiosis and microvesicle formation.
3. Persistent stimulation leads to parakeratosis (thickened stratum corneum with retained nuclei), acanthosis, and hyperkeratosis.
Psoriasis is a chronic inflammatory skin disease characterized by _________ __________.
Is psoriasis familial? How common is it? At what age does it usually manifest?
Yeah familial (1/3 have family Hx, 65% monozygotic twin concordance). It affects 1-2% of the worldwide population. Can arise at any age but usually does in late adolescence.
Psoriasis is associated with increased risk of _____ _______, ________, and ______.
heart attack, strokes and arthritis
True or false: the pathogenesis of psoriasis is poorly understood and likely multifactorial.
It is thought that _________ of epidermal proliferation and an abnormality in the ________ ________ produce psoriatic lesions.
deregulation of epidermal proliferation and an abnormality in the dermal microcirculation
Describe the microcirculatory changes that are seen in psoriasis (2).
1. Capillary loops of dermal papillae become venular, showing multiple layers of basal lamina material.
2. Lots of neutrophils at the tips of dermal papillae, and they migrate into the epidermis and stratum corneum.
What areas of the body are most often affected by psoriasis (6)?
Elbows, knees, scalp, lumbosacral areas, intergluteal cleft, glans penis
Describe the gross appearance of a typical psoriatic lesion (2).
1. Well-demarcated pink or salmon colored plaque
2. Covered by loosely adherent scale that is silver-white
Nail changes occur in ___% of cases of psoriasis. Describe these changes (5).
1. Yellow-brown color
4. Separation of the nail plate from the underlying bed
5. Thickening and crumbling
Describe the microscopic changes seen in a psoriatic lesion. (5)
1. Increased cell turnover --> epidermal thickening (acanthosis) with regular downward elongation of the rete bridges.
2. Mitotic figures seen ABOVE the basal layer.
3. Thinned or absent stratum granulosum.
4. Extensive overlying parakeratotic scale.
5. Neutrophils form small aggregates with spongiotic foci in the epidermis and stratum corneum.
Easier: acanthosis, parakeratosis, neutrophils everywhere, mitotic figures above the basal layer, thin or absent stratum granulosum.
What happens when you scrape off the scale of a psoriatic lesion?
Auspitz sign - multiple minute bleeding points
What is verrucae (warts) and what causes them?
Cutaneous tumors caused by low-risk HPV (no transforming potential)
How do warts spread?
Direct contact - can be autoinoculation, too
Do verrucae spontaneously regress?
Usually within 6 months to 2 years
Describe how HPV causes warts.
It subverts cell cycle control to allow for increased proliferation and survival of epithelial cells and new virus production. Normal immune response limits growth. If immunocompromised --> high numbers, large wart sizes.
Describe the microscopic morphological changes seen in verrucae (4).
1. Epidermal hyperplasia that is UNDULANT (wave-like).
2. Koilocytosis - cytoplasmic vacuolization (perinuclear halo).
3. Prominent keratohyaline granules.
4. Jagged eosinophilic intracytoplasmic protein aggregates.
What are the two types of verrucae?
verruca vulgaris (common wart), verruca plana (plantaris and palmaris are subtypes)
Describe ten changes seen in a common wart (verruca vulgaris). What HPV types is it associated with?
1. Elevated papule with a verrucous, rough, pebble-like surface.
2. Single or multiple.
3. Often found on dorsal surfaces of hands or on the face.
4. Gray-white or tan.
5. Flat or convex.
6. 0.1-1 cm
8. Papillary epidermal hyperplasia and koilocytes.
9. Radiate symmetry.
10. Prominent keratohyalin granules.
HPV 2, 4, no malignant potential
Describe the morphological changes seen in verruca plana (flat warts). What HPV types cause it?
Rough, scaly lesions, 1-2 cm, can be confused with calluses. They grow inwards, and are found on the palm or soles of the feet.
HPV 3, 10 cause it
What is actinic keratosis?
A premalignant epithelial lesion with dysplasia.
Describe the microscopic morphologic changes seen in actinic keratosis (4).
1. Thickened dermis (hyperkeratosis).
2. Blue-gray elastic fibers (solar elastosis) from chronic sun damage.
3. Stratum corneum is thickened with retained nuclei (parakeratosis).
4. Lower portions of the epidermis show atypia with hyperplasia of basal cells.
What causes actinic keratosis? Can it become malignant?
Sun damage --> UV p53 damage. They can progress to carcinoma in situ.