Skin Pathology Flashcards
Actopic Dermatitis (eczema)
- pruritic, erythematous, oozing rash with vescicles and edema, often involved face and flexor surfaces
- Type 1 hypersensitivity
Contact dermatitis
- pruritic, erythematous, oozing rash with vesicles and edema
- arises upone exposure to allergens like poison ivy and whatnot
- tx involves removal of the ffending agent and topical glucocorticoids, if needed
Acne vulgaris
- Comedones (black and white heads), pustules (pimples), and nodules
- chronic inflammation of hair follicles and associated sebaceous glands
- increase in sebum production
- propionibacterium acnes infection… FA’s released, results in pustule or nodule formation
- Tx includes benzoyl peroxide and Vit A derivatives, which reduce keratin production
Psoriasis
- well-circumscribed, salmon colored plaques with silvery scale, usually on extensor surfaces and scalp, pitting of nails may also be present
- due to excessive keratinocyte proliferation
- autoimmune, HLA-C
- Lesions in areas of trauma
Histology of psoriasis?
- acanthosis
- parakeratosis
- collections of neutrophils in the stratum corneum (munro microabscesses)
- thinning of epidermis above elongated dermal papillae… results in bleeding when scale is picked off (auspitz sign)
Tx for psoriasis
-corticosteroids, UV light with psoralen, or immune modulating therapy
Lichen Planus
- The p disease
- Pruritic, planar, polygonal, purple papules\, often with reticular white lines on their surface…. commonly involves wrists, elbows, and oral mucosa
What does the oral involvement of lichen planus manifest as?
-whickham striae
Histo for lichen planus
-inflammation of the derma epidermal junction with a “saw tooth” appearance
Pemphigus vulgaris
- AI destruction of desmosomes b/w keratinocytes
- IgG antibody against desmoglein (type 2 hypersensitivity)
- Presents as skin and ORAL mucosa bullae
- rupture easily… dried crust
- IF highlights IgG surrounding keratinocytes in a “fish net” pattern
What gives pemhpigus vulgaris its tombstone appearance?
-basal layer cells remain attached to basement membrane via hemidesomosomes
Bullous Pemphigoid
- AI destruction of hemidesmosomes betwen basal cells and the underlying basement membrane
- IgG ab against hemidesmosome components(BP180) of basement membrane
Presentation of bullous pemphigoid
- blisters of the skin, usually in the elderly
- oral mucosa is spared
- do NOT rupture easily… clinically milder than pemphigus vulgaris
What will IF staining look like in bullous pemphigoid?
- highlights IgG along basememnt membrane (linear pattern)
- pemphigus vulgaris was a fish net
Dermatitis herpetiformis
- AI deposition of IgA at the tips of dermal papillae
- Presents as Pruritic vesicles and bullae that are grouped
- strong association with celiac disease; resolves with gluten-free diet
Erythema multiforme (EM)
- hypersensitivity rxn: targetoid rash and bullae: central epidermal necrosis surrounded by erythema
- HSV infection
What is it called if we see EM with oral mucosa/lip involvement and fever?
- Stevens-Johnson syndrome (SJS)
- toxic epidermal necrolysis, severe form of SJS with diffuse sloughing of skin… looks like large burn… adverse drug rxn
Seborrheic Keratosis
-Benign squamous proliferation; common tumor in the elderly
Seborrheic keratosis (SK) presentation
- raise, discolored plaques on the extremities or face
- often has a coin-like, waxy, stuck-on appearance
- characterized by keratic pseudocysts on histology
What is Leser-Trelat sign?
-the sudden onset of multiple seborrheic keratoses and suggests underlying carcinoma of the GI tract
What mutation is associated with SK?
-FGFR3
Mutation for Paget’s?
-SQSTM1
Mutation for fibrous dysplasia
-GNAS1
What are Acrochondons?
- neck and axilla
- hormonally sensitive
- Birt-Hogge-Dube syndrome
- They’re freaking skin tags!!!!
What are eccrine poromas?
-on palms and soles
What is erythema nodosum?
- B strep
- tender erythematous plaques…. poorly defined
Acanthosis Nigricans
- epidermal hyperplasia with darkening of the skin… often involves the axilla or groin
- associated with insulin resistance or malignancy (especially gastric carcinoma)
Basal Cell carcinoma
- Malignant proliferation of the basal cells of the epidermis
- most common cutaneous malignancy
- risk factors stem from UVB-induced DNA damage and include prolonged exdposure to sunlight, albinism, and xeroderma pigmentosum
Presentation of BCC
- elevated nodule with a central, ulcerated crater surrounded by dilated vessels
- Pink, pearl like papule
- classic location is the upper lip
Histology of BCC
-nodules of basal cells with peripheral palisading (means lining up against something)
Tx for BCC
- surgical excision
- metastasis is rare
Squamous cell carcinoma
- Malignant proliferation of squamous cells characterized by formation of keratin pearls
- sun is risk factor
- Immunosuppressive therapy can cause this as well
Presentation of SCC
-ulcerated, nodular mass, usually on the face, classically involving the lower lip
Tx for SCC
- excision
- mets are uncommon
What is actinic keratosis
-a precursor lesion of squamous cell carcinoma and presents as a hyperkeratotic, scaly plaque, often on the face, back, or neck
What is keratoacanthoma
-well differentiated SCC that develops rapidly and regresses spontaneously; presents as a cup-shaped tumor filled with keratin debris
What is the gene is wrong with BCC?
-PATCH abnormality
What syndrome is associated with BCC?
-Ghorlin syndrome
Mutation for dermato fibrosarcoma protuberans?
- translocation involving PDGFB and COL1A1
- increased secretion of PDFGB… drives tumor cell growth
- “pinwheel” pattern= storiform
- overlying dermis is generally thinned
where are melanocytes?
-in the basal layer
Where are melanocytes derived from?
-neural cerest
Where is melanin made?
-in melanosomes
Vitiligo
localized loss of skin pigmentation
-due to AI destruction of melanocytes
-
Albinism
- congenital lack of pigmentation
- enzyme defect (tyrosinase) impairs melanin production
- may involve the eyes or skin or both
- increased risk of SCC, BCC, and melanoma due to reduced protection against UVB
Freckle (Ephelis)
- Small, tan to brown macule; darkens when exposed to sunlight
- due to increased number of melanosomes
- melanocytes are not increased***
Melasma
- Mask-like hyperpigmentation of the cheeks
- associated with pregnancy and oral contraceptives
Nevus (mole)
- benign neoplasm of melanocytes
- congenital nevus is present at birth; often associated with HAIR
- acquired nevus arises later in life
Progression of an acquired nevus
- beings as nests of melanocytes at the dermal-epidermal junction(junctional nevus); most common mole in children
- grows by extension into the dermis (compound nevus)
- junctional component by a flat macule or raised papule with symmetry, sharp borders, evenly distributed color, and small diameter (<6mm)
What is a dysplastic nevus a precursor to?
-melanoma
Mutation for Melanoma?
-CDKN2A
Melanoma
- malignant neoplasm of melanocytes; most common cause of death from skin cancer
- risk facors from UVB
- Presents as a mole-like growth wtih ABCD
What does ABCD stand for?
- asymmetry
- borders are irregular
- color is not uniform
- diameter> 6mm
What are the 2 growth phases for melanoma?
- Radial growth…. horizantally along epidermis… low risk
- Vertical growth into deep dermis: increased risk
What is the most important prognostic factor is predicting mets for Melanomas?
-depth of extension (breslow thickness)
Superficial spreading melanoma
- most common subtype
- dominant early radial growth
- results in good prognosis
Lentigo maligna melanoma
- lentiginous proliferation (radial growth); good prognosis
- grows along ED junction
- older men
Nodular melanoma
- early vertical growth
- poor prognosis
Mutation for nodular melanoma
-HMB45
Acral lentiginous melanoma
- arises on the palms or soles, often in dark-skinned individuals
- not related to UV light exposure***
Impetigo
- Superficial bacterial skin infection
- staph Aureus
- children
- honey colored serum
- histo: accumulation of neutrophils beneath the stratum corneum
- bullous form in children
Cellulitis
- deeper infection, usually due to S aureus or S pyogenes
- red, tender, swollen rash with fever
- recent surgery, trauma, or insect bite are risk factors
- can progress to neecrotizing fasciitis with necrosis of subcutaneous tissues due to infection with anaerobic “flesh -eating” bacteria
- production of CO2 leads to crepitus
- Surgical emergency if that happens
Verruca (Wart)
- flesh-colored papules with a rough surface
- Due to HPV (11+16) infection of keratinocytes
- koilocytic change
- hands and feet are common locations
Which HPV subtypes will give us SCC?
- 5 and 8
- they produce variant E6 ptns that do not affect p53
Molluscum contagiosum
- poxvirus
- dumbebell shaped DNA
- Firm, pink, umbilicated papules due to poxvirus; affected keratinocytes show cytoplasmic inclusions on Geimsa stain (molluscum bodies)
- Most often arise in children; also occur in sexually active adults and immunocompromised individuals
- spread by direct contact
Urticaria
- localized mast cell degranulation
- microvascular hyperpermeabiliy
- produces prutitic edematous plaques called wheals
- 20-40
What does eczematous dermatitis typically result from?
-T cell-mediated inflammatory reactions (type 4 hypersensitivity)
What cell is the problem in erythema multiforme?
-CD8+ T cells
What will we see on histo for EM?
-accumulation of lymphocytes along the dermoepidermal junction
What cell is the problem in ezcematous dermatitis?
-Langerhans cells… they are the ones that initiate the inflammatory response
Which gene is associated with psoriasis?
HLA-C
-particularly: HLA-Cw*0602 allele
is seborrheic dermatits a disease of the sebaceous glands?
-no, it’s the inflammation of the epidermis
Common presentation for SD in the scalp?
-dandruff
What is found at the ostia of hair follicles in Seborrheic dermatitis?
-mounds of parakeratosis containt neutrophils and serum (follicular lipping)
What does lichen planus leave behind after it resolves?
-postinflammatory hyperpigmentation
What is the Koebner phenomenon?
-when psoriatic lesions are induced in susceptible individuals by local trauma
What other disease besides psoriasis does the Koebner phenomenon happen?
- lichen planus
- remember, comes from local trauma
What are Civatte bodies?
- anucleate, necrotic basal cells that become incorporated into the inflamed papillary dermis
- happens whenever basal keratinocytes are destroyed… but characteristic of lichen planus
Pemphigus vegetans
-large, moist, verrucous, vegetating plaques studded with pustules on the groin, axillae, and flexural surfaces
Pemphigous foliaceus
- it’s in brazil
- more superficial
- erythema and crusting
- mucous membranes rarely effected
Pemphigus erythematosus
- less intense than foliaceus
- malar area of the face in a lupus like fashion
Paraneoplastic pemphigus
-occurs in association with various malignancies, most commonly non-hodgkin lymphoma
What age ppl get bullous pemphigoids?
-older ppl
Antibodies against what hemidesmosome component is present in bullous pemphigoid?
-BPAG2
What disease will respond to a gluten free diet?
- the one that is IgA related
- Dermatitis herpetiformis
- remember, this is the subepidermal blister
Morphology of Dermatitis herpetiformis
- lesions are b/l, symmetrical, and grouped
- extensor surfaces
- fibrin and neutrophils accumulate selectively at the tips of dermal papillae: microabscesses
- IF will show discontinuous, granular deposits of IgA that selectively localize in the tips of the DERMAL PAPILLAE
Epidermolysis bullosa
- group of disorders caused bye inherited defects in structural ptns
- common feature is proclivity to form blisters at sites of prssure, rubbing, or trauma, at or soon after birth
In the most common type of epidermolysis bullosa, what is the mutations?
- most common type is the simplex type
- mutations in genes encoding keratin 14 or 5
Porphyria
- group of uncommon inborn or acquired disturbances of porphyrin metabolism
- scarring that is exacerbated by exposure to sunlight
- subdermal vesicles
- blood vessels have walls that are thickened by glassy deposits of serum proteins including Ig’s
difference betwen open and closed comedones
- open: small follicular papules containing a central black keratin plug… result of oxidation of melanin
- Closed comedones: without a visible central plug… the keratin plug is trapped beneath the epidermal surface… these lesions are potential sources of follicular rupture and inflammation (these ones are identifiable only microscopically)
Rosacea
- cathelicidin is present, result of alternative processing by proteases such as kallikrein 5
- rhinophyma is stage 4: permanent thickening of the nasal skin by confluent erythematous papules and prominent follicles
Panniculitis
- inflammatory rxn in the subcutaneous adipose tissue
- erythema nodosum
- erythema induratum
Erythema nodosum
- palpated, not seen
- infections
- poorly defined, exquisitely tender, erythematous plaques and nodules
Erythema induratum
- adolescents and menopausal women, uncommon
- primary vasculitis of deep cessels
- slightly tender nodule that usually goes on to ulcerate
- usually no associated disease.. it just kinda happens
factitial panniculitis
-caused by self-inflicted trauma or injection of foreign toxic substances
Weber-Christian disease
-crops of erythematous plaques or nodules, predominantly on lower extremities
