Dermatopathology II Flashcards
Dermatofibroma (5):
- Benign fibrous histiocytoma
- Slow growing
- Flesh-colored to pigmented papule
- Displays the “dimple sign”
- Fibrous reaction to some past trauma
Dermatofibroma histological features (3):
- Benign proliferations of fibroblasts with collagen
- Whirling fibroblasts with collagen bundles
- May be overlying hyperkeratosis and hyperpigmentation
Uticaria pigmentosa (2):
- Type of mastocytosis
- Usually multiple mastocytomas - round to oval, red-brown papules and plaques, pruritic and may blister, appear shortly after birth
Systemic mastocytosis (3):
- Usually adults
- Skin lesions similar to uticaria pigmentosa plus:
- Multi-organ mast cell infiltration
Mastocytoma histologic features (4):
- Metachromatic granules within dendritic mast cells
- Monomorphous dermal infiltrate
- No epidermotropism
- Fried egg cells
Ichthyosis:
Disorders which impair epidermal maturation
Irritant contact dermatitis (3):
- Substance has direct toxic effects on the skin
- Not an immunologic condition
- Rash begins shortly after exposure
Allergic contact dermatitis (3):
- Cell-mediated, delayed-type hypersensitivity reaction (Type IV)
- Sensitization of skin occurs 1-2 weeks after 1st exposure to allergen
- Reexposure causes dermatitis in hours to days
Atopic dermatitis (2):
- Chronic, waxing and waning, extremely pruritic condition beginning in the 1st year of life
- Condition is worse in winter due to decreased humidity
Lichenification:
Epidermal thickening characterized by visible and palpable skin thickening with accentuated skin lines
- Chronic dermatitis leads to this
Nummular dermatitis (3):
- Coin shaped
- Itchy red plaques with vesicles and distinct borders
- More likely in young adults
Asteatotic dermatitis (3):
- Winter itch
- Older people in winter
- Dry, cracked skin that becomes itchy
Erythema multiforme (EM) (4):
- Immune-mediated, hypersensitivity reaction resulting in epidermal cell injury
- Epidermal cells are attacked by CD8+ cytotoxic T-cells; target Ag unknown
- Erythematous macules and papules, vesicules and bullae on extremities that are strikingly symmetric
- Target lesions are diagnostic
Stevens-Johnson Syndrome (4):
- 10-30% Body surface involvement
- More severe than EM
- Involvement of mucous membranes including mouth and conjunctivae
- Systemic manifestations may include fever, difficulty eating, renal failure and sepsis
Toxic Epidermal Necrolysis (TENs) (4):
- > 30% body surface involvement
- More severe than Stevens-Johnson syndrome
- Dermatologic emergency
- Detachment of large areas of epidermis
Pityriasis rosea (6):
- Subacute spongiotic dermatitis
- Most common in winter
- Get initial herald patch that resembles ring worm
- Progresses to generalized oval, slightly elevated, scaling papules that are smaller
- Lesions pink with scaling near the border
- Christmas tree pattern
Venous insufficiency (2):
- Venous incompetence causes increased hydrostatic pressure and capillary damage leading to extravasation of RBCs and serum
- Starts as edema and hyperpigmentation and leads to pruritic erythema and stasis dermatitis
Psoriasis (5):
- Accelerated proliferation of skin cells resulting in scaling
- Chronic condition with exacerbations and remissions
- Well-demarcated, erythematous plaques and papules with silver scaling
- Symmetrical
- Auspitz’s sign
Auspitz’s sign:
Pinpoint bleeding on removed of scale
Psoriasis histologic features (4):
- Downward elongation of rete ridges
- Thinning of overlying stratum granulosum with parakeratosis above
- Aggregates of neutrophils with surrounding spongiosis
- Capillaries in dermal papillae are brought close to the surface
Arthritis multilans:
Very destructive form of psoriatic arthritis with significant periarticular bone resorption.
Seborrheic dermatitis (4):
- Chronic inflammatory process affecting areas rich in sebaceous glands
- Malassezia furfur
- Yellow greasy scaly patches with surrounding erythema
- Asymptomatic but may be itchy
Lichen planus (6):
- Idiopathic inflammatory disorder
- Pruritic, purple, polygonal, planar, papules, plaques
- Most common on wrists and ankles
- Mucous membrane involvement is common
- Wickhams striae
- Koebner phenomenon
Wickham’s striae:
Fine reticulated white lines
Koebner phenomenon:
Trauma to skin and stress can cause exacerbations
Systemic lupus erythematosus:
Multisystem autoimmune disease involving connective tissues and blood vessels
Malar rash:
SLE:
- Butterfly rash, erythematous, confluent, macular eruption with clear borders that spares nasolabial folds
