Skin Pathology Flashcards
Layers of epidermis from surface to basement membrane
Stratum corneum — keratin and anucleate cells
Stratum granulosum — granules in keratinocytes
Stratum spinosum — desmosomes between keratinocytes
Stratum basalis — stem cell layer; regenerates new epidermis
Basement membrane
______ _______ = pruritic, erythematous, oozing rash with vesicles and edema, often involving face and flexor surfaces. It is a type ____ HSR associated with asthma and allergic rhinitis.
Atopic dermatitis; Type I HSR
Pruritic, erythematous, oozing rash with vesicles and edema that arises upon exposure to allergens
Contact dermatitis
Contact dermatitis = Pruritic, erythematous, oozing rash with vesicles and edema that arises upon exposure to allergens. Examples of irritants include poison ivy and nickel jewelry, which would constitute a type ___ HSR. Other irritants include chemicals like detergents, or drugs like PCN. Treatment is removal of offending agent and topical steroid if needed
Type IV HSR
Acne vulgaris may include comedones (whiteheads and blackheads), pustules (pimples), and nodules. Acne is due to chronic inflammation of _______ and ________. Hormone-related increases in sebum and excess keratin block follicles (comedones). __________ infection leads to inflammation (pustules and nodules)
Hair follicles; sebaceous glands; Propionibacterium acnes
Treatment for acne may include _____ ____ as an antimicrobial, as well as vitamin A derivatives like ______ which reduce keratin production
Benzoyl peroxide; isotretinoin
Psoriasis involves well-circumscribed salmon-colored plaques with silvery scale, usually on extensor surfaces and scalp. Pitting of nails may also be present. This condition is due to excessive ______ proliferation and may have autoimmune etiology. It is associated with HLA-____. Lesions often arise in areas of trauma (environmental trigger).
Treatment includes corticosteroids, UVA light with _____, and immune-modulating therapy
Keratinocyte; HLA-C
Psoralen
Inflammatory dermatosis characterized by pruritic, planar, polygonal, purple plaques, often with reticular white lines on surface (wickham striae), commonly involving wrists, elbows, and oral mucosa
Key histological finding is inflammation at dermal-epidermal junction (sawtooth appearance).
Lichen planus
The etiology of lichen planus is unknown, but it is associated with chronic ________ infection
Hepatitis C
Classic histology shows hyperplasia with increased thickness of epidermis (acanthosis), excess keratin on surface of epidermis with retention of nuclei (parakeratosis), collections of neutrophils at surface (monroe microabscesses), and elongation of dermal papillae (may result in pinpoint bleeds = auspitz sign)
Psoriasis
Autoimmune destruction of desmosomes due to IgG antibody against desmoglein; immunofluorescence highlights IgG surrounding keratinocytes with ‘fish net’ appearance. May involve oral mucosa as well
Pemphigus vulgaris
[primarily affects stratum spinosum resulting in acantholysis. Note that basal layer remains intact because they are attached by hemidesmosomes — tombstone appearance]
Autoimmune destruction of hemidesmosomes due to IgG antibody against basement membrane; presents as subepidermal blisters of skin that spare the oral mucosa. These are tense bullae that do not rupture easily
Bullous pemphigoid
Autoimmune deposition of IgA at tips of dermal papillae, presenting as pruritic vesicles and bullae that are grouped; strong association with celiac disease
Dermatitis herpetiformis
Hypersensitivity reaction with targetoid rash and bullae; most commonly associated with HSV infection
Erythema multiforme
[can also be seen with mycoplasma, drugs like PCN, autoimmunity (lupus, etc.), malignancy, etc]
Erythema multiforme with oral mucosa involvement and fever is termed ______________.
______________ is a severe form of the above condition, characterized by diffuse sloughing of skin resembling a large burn. This most often arises due to adverse drug reaction
Stevens johnson syndrome
Toxic epidermal necrolysis
Epithelial tumor classified as benign squamou proliferation; common in the elderly. Gross exam reveals raised discolored plaque, with “stuck-on” appearance. Histology reveals pseudocysts.
Seborrheic keratoses
Sudden onset of many seborrheic keratoses is termed _____ sign and suggests underlying carcinoma of the ______
Leser-Trelat; GI tract
Epidermal hyperplasia with darkening of skin (‘velvet like’ skin), often involving groin or axilla. Associated with insulin resistance or malignancy
Acanthosis nigricans
Basal cell carcinoma is a malignant proliferation of basal cells of the epidermis. What are some risk factors?
Prolonged exposure to sunlight
Albinism
Xeroderma pigmentosum
[All related to excess UVB exposure]
Classic histological finding in basal cell carcinoma
Peripheral palisading
Treatment for BCC is surgical excision.
T/F: metastasis of BCC is rare
True
SCC is a malignant proliferation of squamous cells. Like BCC, risk factors include exposure to UVB sunlight and conditions like albinism and xeroderma pigmentosum. What are 3 additional risk factors for SCC specifically?
Immunosuppressive therapy
Arsenic poisoning
Chronic inflammation (e.g., scar from burn or draining sinus tract)
SCC presents as ulcerated, nodular mass usually on the face, classically involving the lower lip (if upper lip, think more BCC). Treatment is excision.
T/F: metastasis is common
False — metastasis is uncommon
Precursor lesion to SCC, presents as hyperkeratotic, scaly plaque on face, back, or neck
Actinic keratosis
Well-differentiated SCC that develops rapidly and regresses spontaneously; presents as a cup-shaped tumor filled with keratin debris
Keratoacanthoma
Melanocytes are responsible for skin pigmentation. They are present in the _______ layer of the epidermis and are derived from ______ ______. They synthesize melanin in melanosomes
Basal; neural crest
______ occurs due to localized loss of skin pigmentation due to autoimmune destruction of melanocytes
Vitiligo
Albinism is a congenital lack of pigmentation due to enzyme defect (usually _______) that impairs melanin production. May involve eyes (ocular form) or both the eyes and skin (oculocutaneous form). These pts are at increased risk for skin cancer.
Tyrosinase
Freckles are small, tan-brown macules that darken when exposed to sunlight. Why are freckles darker than the rest of the skin?
They have increased numbers of melanosomes
[NOT DUE TO INCREASED MELANOCYTES]
Mask-like hyperpigmentation of the cheeks associated with pregnancy and oral contraceptives
Melasma
Benign neoplasm of melanocytes; when congenital they are present at birth and often associated with hair
Nevus (mole)
[note that melanoma will not have hair growing out of it]
Acquired nevi arise later in life. A _______ nevus is the most common mole in children. A _______ nevus describes a mole that eventually extends into the dermis. A _______ nevus is the most common mole in adults
Junctional; compound; intradermal
T/F: Risk factors for melanoma are similar to SCC and BCC in that they involve UVB exposure and conditions like albinism and xeroderma pigmentosum
True
Dysplastic nevus syndrome is a ______ _____ inherited disorder characterized by formation of dysplastic nevi that may progress to melanoma
Autosomal dominant
Melanoma are distinguished from benign nevi by the ABCDs — what are the ABCDs?
Asymmetry
Borders are irregular
Color is not uniform
Diameter > 6 mm
Melanoma is characterized by what 2 growth phases and how do they correlate with risk of metastasis?
Radial growth horizontally along epidermis and superficial dermis — low risk of metastasis
Vertical growth into deep dermis — high risk of metastasis (key risk for metastasis is depth of invasion)
Subtype of melanoma characterized by radial growth; good prognosis
Lentigo maligna melanoma
Most common subtype of melanoma; characterized by dominant early radial phase and a good prognosis
Superficial spreading melanoma
Subtype of melanoma characterized by early vertical phase and a poor prognosis
Nodular melanoma
Subtype of melanoma that arises on palms or soles, often in dark-skinned individuals; is NOT related to UV light exposure
Acral lentiginous melanoma
Superficial bacterial skin infection most commonly due to S aureus or S pyogenes, commonly affects children and is extremely contagious; presents as erythematous macules that progress to pustules on the face, eventually resulting in erosions and dry, crusted, honey-colored serum
Impetigo
Deeper (dermal) infection usually due to S aureus or S pyogenes that presents as red, tender, swollen rash with fever. Risk factors include recent surgery, trauma, and insect bite.
Cellulitis
Cellulitis may progress to ______ _______, which is characterized by necrosis of subcutaneous tissue due to infection with anaerobic ‘flesh-eating’ bacteria. Production of ______ leads to crepitus. This is a surgical emergency!
Necrotizing fasciitis; CO2
Staphylococcal scalded skin syndrome results in sloughing of skin with erythematous rash and fever, leading to significant skin loss. This is caused by S aureus infection, producing ___________ toxins that result in epidermolysis of the stratum _______
Exfoliative A and B; granulosum
Verruca (wart) are flesh-colored papules with rough surface due to ______ infection of keratinocytes. Hands and feet are common locations
HPV
________ _________ = firm, pink umbilicated papules due to _____virus infection of keratinocytes. Most often arise in children; also occur in sexually active adults and immunocompromised individuals.
Molluscum contagiosum; poxvirus
