Chapter 25: Skin - Dermatoses, Blistering , Epidermal Appendage, and Infections Flashcards
Ichthyosis is a group of inherited disorders that results in what?
- Chronic, excessive keratin buildup (hyperkeratosis) –> fishlike scales
- Defective desquamation
All forms of ichthyosis exhibit a buildup of what; morphologic appearance?
Buildup of compated stratum corneum that is assoc. w/ loss of normal basket-weave pattern
Angioedema is closely related to urticaria and is characterized by what?
Edema of the deeper dermis and SQ fat
What are the histologic changes seen in Urticaria?
- Sparse superficial perivenular infiltrate consisting of mononuclear cells
- Collagen bundles are more widely spaced than in normal skin –> clear spaces in between
Urticaria (hives) is a common disorder of the skin characterized by what?
- Localized mast cell degranulation —> dermal microvascular hyperpermeability
- Results in pruritic edematous plaques (wheals)
Acute eczematous dermatitis is which type of hypersensitivity?
T-cell mediated inflammatory rxn (type IV hypersensitivity)
All types of eczematous dermatitis are characterized by what type of lesions and what occurs if persistent?
- Red, papulovesicular, oozing, and crusted lesions
- If persistent –> develop reactive acanthosis and hyperkeratosis that produce red scaling plaques
Which edematous finding characterizes acute eczematous dermatitis; how does this differ from urticaria?
- Spongiosa: edema seeps into the intercellular spaces of the epidermis, splaying apart keratinocytes, particularly in stratum spinosum
- In urticaria the edema is restricted to superficial dermis
In acute eczematous dermatitis, mechanical shearing of intercellular attachment sites (desmosomes) and cell membranes by progressive accumulation of intercellular fluid may result in formation of what?
Intraepidermal vesicles
Erythema multiforme is characterized by keratinocyte injury mediated by what?
Skin-homing CD8+ cytotoxic T cells
Which severe febrile form of erythema multiforme is often seen in children with lesions involving not only the skin but also the lips and oral mucosa, conjunctiva, uretha, and genital/perianal areas?
Stevens-Johnson Syndrome
Which life threatening complication may arise from Steven-Johnson syndrome?
Life-threatening sepsis as a result of 2’ infection due to loss of skin integrity
“Targetoid” lesions are characteristic of what?
Erythema Multiforme
What is interface dermatitis as it relates to erythema multiforme?
Lymphocyte infiltration along dermoepidermal jct, asooc. with degenerating and necrotic keratinocytes
Psoriasis is strongly linked to which HLA gene locus?
HLA-C; paricularly HLA-Cw*0602
What is the Koebner phenomenon and what 2 chronic inflammatory dermatoses can it be seen in?
- Induction of lesions in susceptible pt’s by local trauma, starts a self-perpetuating local inflammatory response
- Seen with Psoriasis and Lichen Planus
Which body regions most often affected in Psoriasis; how do they lesions appear?
- Skin of elbows, knees, scalp, lumbosacral areas, intergluteal cleft, and glans penis
- Well-demarcated, pink to salmon-colored plaque covered by loosely adherent silver-white scale
What are the nail changes seen in some pt’s with Psoriasis?
Yellow-brown discoloration (oil-slick), with pitting, dimpling, separation of the nail plate from underying bed (onycholysis), thickening, and crumbling
What is the characteristic histologic picture of established lesions seen with Psoriasis?
- Marked epidermal thickening (acanthosis)
- Downward elongation of the rete ridges –> “test tubes in a rack”
- Abundant mitotic figures
- Stratum granulosum is thinned or absent, and extensive overlying parakeratotic scale seen
Dilated, tortuous blood vessels within dermal papillae of Psoriasis lesions leads to what characteristic sign when scales are lifted from a plaque?
Auspitz sign: mult, minute, bleeding points when scale lifted from plaque
Which immune cells form aggregates within spongiotic foci of the superficial epidermis (spongiform pustules) and within the parakeratotic stratum corneum (munro microabscesses) in psoriasis?
Neutrophils (PMNs)
Which chronic inflammatory dermatitis classically involves regions with a high density of sebaceous glands such as the scalp, forehead (especially the glabella), external auditory canal, retroauricular area, nasolabial folds, and presternal area?
Seborrheic Dermatitis
What is the most common clinical expression of Seborrheic Dermatitis of the scalp?
Dandruff
What are the “Six P’s” of lichen planus?
Pruritic, Purple, Polygonal, Planar, Papules, and Plaques
Which chronic inflammatory dermatosis is a self-imited disorder of skin and mucosa, resolving spontaneously in 1-2 years?
Lichen Planus
Which complication may arise as a result of the chronic mucosal and paramucosal lesions associated with lichen planus?
SCC