Skin pathology Flashcards
1
Q
Atopic dermatitis
A
- Pruritic, erythematous, oozing rash with vesicles and edema
- Often involves face and flexor surfaces
- Type I HSR, associated wit asthma and allergic rhinitis
2
Q
Contact dermatitis
A
- Pruritic, erythematous, oozing rash with vesicles and edema
- Arises upon exposure to allergens
- Irritants: poison ivy and nickel jewelry (type IV HSR), irritant chemicals (e.g., detergents), drugs (e.g., PCN)
- Treatment: removal of offending agent, topical steroids, if needed
3
Q
Acne vulgaris
A
- Comedones (whiteheads and blackheads)
- Pustules (pimples)
- Nodules
- Due to chronic inflammation of hair follicles and sebaceous glands
- Hormone-related increase in sebum and excess keratin block follicles (comedones)
- Propionibacterium acnes infection leads to inflammation (pustules or nodules)
- Treatment: benzoyl peroxide
4
Q
Psoriasis
A
- Well-circumscribed salmon-colored plaques with silvery scale. Ausspitz sign
- Usually on extensor surfaces of elbows and knees, as well as the scalp and sacral area
- Due to excessive keratinocyte proliferation
- Possible autoimmune etiology
- Associated wit HLA-C allele on PSORS1 on chromosome 6
- 30% - facility history, HLA B13, 17
- Lesions often arises in areas of trauma (environmental trigger)
- Treatment: corticosteroids, UVA-light with psoralen, immune-modulating therapy
5
Q
Varicella (chickenpox)
A
- Viral infection of childhood
- Characterized by fever and a generalized vesicular eruption
- The varicella-zoster virus may remain latent for years in dorsal root ganglia
6
Q
Pemphigus vulgaris
A
- Autoimmune destruction of desmosomes
- Formation of severe intraepidermal bullae is characteristic
- First lesions often occur in the oral mucosa, and extensive skin involvement follows
- Due to IgG antibody against desmoglein
- IF highlights IgG surrounding keratinocytes (‘fish net’)
- Rupture easily - leaving large denuded surfaces subject to secondary infection
7
Q
Lichen planus
A
- Pruritic, planar, polygonal, purple papules
- Often with reticular white lines on surface (Wickham striae)
- Commonly involves wrists, elbows, and oral mucosa
- Inflammatory infiltrate composed of lymphocytes at the dermal-epidermal junction (‘saw-tooth’ appearance)
- Presence of apoptotic keratinocytes mainly in basal cell layer
- Etiology is unknown - associated with chronic hepatitis C virus infection and vaccination against hepatitis
8
Q
Bullous pemphigoid
A
- Resembles pemphigus vulgaris, but is much less severe
- Autoimmune destruction of hemidesmosome
- IgG autoantibodies agianst epidermal BM
- Presents as subepidermal blisters of skin filled with fluid containing eosinophils (between dermis and epidermis); oral mucosa is spared
- Tense bullae do not rupture easily
9
Q
Dermatitis herpetiformis
A
- Due to autoimmune deposition of IgA at tips of dermal papillae
- Presents as pruritic vesicles and bullae that are grouped
- Usually involves the extensor surfaces of the knees and elbows, scalp, upper back, and sacral area
- Dermal microabscesses with neutrophils and eosinophils at the tips of dermal papillae
- Associated with celiac disease
- Resolve with a gluten-free diet
10
Q
Erythema multiforme
A
- Presents with multiple type of lesions, including macules, papules, and vesicles
- Characteristically associated with a ‘target’ lesion resembling an archer’s bull’s eye
- Most commonly associated with HSV infection
- Usually hypersensitivity to coexistent infectious agents, various drugs, a concomitant connective tissue disorder, or an associated malignancy
- EM variants: Stevens-Johnson syndrome, Toxic epidermal necrolysis
11
Q
Vitiligo
A
- Localized loss of pigmentation
- Due to autoimmune destruction of melanocytes by toxic intermediates of melanin production or by neurochemical factors
- Associated with autoimmune disorders, such as Graves disease and Addison disease
12
Q
Albinism
A
- Congenital lack of pigmentation
(1) Ocular albinism: melanin dysfunction limited to the eyes; X-linked disorder
(2) Oculocutaneous albinism: involves eyes, skin, and hair; predisposes to actinic keratosis, basal and squamous cell carcinoma, and malignant melanoma; most often autosomal recessive - Tyrosine-negative albinism - failure of conversion of tyrosine to DOPA
- Tyrosine-positive albinism - unknown etiology
13
Q
Freckle
A
- Increase of melanin pigment within basal keratinocytes - melanosomes
- Darkens when exposed to sunlight
14
Q
Lentigo
A
- Pigmented macule caused by melanocytic hyperplasia in the epidermis
15
Q
Melanocytic nevus
A
- Lesion classified as a benign tumor or hamartoma
- Nevus cells are derived from melanocytes and ordinarily occur in cluster or nests
(1) Juntional nevus: confined to the epidermal-dermal junction, most common mole in children
(2) Compound nevus: both at the epidermal-dermal junction and in the dermis
(3) Intradermal nevus: cinfined to clusters within the dermis, most common mole in adults
16
Q
Blue nevus
A
- Pigmented nevi that are present at birth
- Characteristically include nodular foci of dendritic, highly pigmented melanocytes in the dermis
17
Q
Spitz nevus
A
- Most often occurs in children
- Generally benign, although an atypical variant with borderline behavior exists
- Often characterized by spindle-shaped cells and can be confused with malignant melanoma
18
Q
Dysplastic nevus
A
- Atypical, irregular pigmented lesion with disorderly proliferation of melanocytes, dermal fibrosis, and often subjacent dermal lymphocytic infiltration
- May transform into malignant melanoma
- Familial in some cases - autosomal dominant inheritance
19
Q
Lentigo maligna
A
- Nonfamilial precursor to lentigo maligna melanoma
- Irregular macular pigmented lesion on sun-exposed skin
- Characterized by atypical melanocytes at the epidermal-dermal junction
20
Q
Molluscum contagiosum
A
- Contagious viral disorder that occurs most often in children and adolescents
- Firm, pink, umbilicated, dome-shaped papules due to a DNA poxvirus
- Transmitted by direct contact
21
Q
Verruca vulgaris
A
- Common wart
- Benign papilloma caused by certain strain of HPV (3 and 10?) infection of keratinocytes
- Flesh-colored papules with rough surface
- Vacuolated cells (kilobytes) in the granular cell layer of the epidermis are characteristic
- Hands and feet are common locations
22
Q
Cellulitis
A
- Deeper (dermal) infection
- Usually due to S. aureus or S. pyogenes
- Presentss as a red, tender, swollen rash with fever
- Risk factors: recent surgery, trauma, insect bite
- Can progress to necrotizing fasciitis
23
Q
Staphylococcal scalded skin syndrome
A
- Sloughing of skin with erythematous rash and fever
- Leads to significant skin loss
- Due to S. aureus infection
- Exfoliative A and B toxins result in epidermolysis of stratum granulosum
24
Q
Actinic keratosis
A
- Premalignant epidermal lesion caused by chronic excessive exposure to sunlight
- Characterized by roughness, scaling, poorly demarcated plaques on the face, neck, upper trunk, or extremities
25
Acanthosis nigricans
- Epidermal hyperplasia with darkening of skin ('velvet-like' skin)
- Sometimes a marker for visceral malignancy (stomach, lung, breast, uterus) and is often seen in the setting of diabetes and other endocrinopathies
- Characterized by acanthosis and hyperpigmentation
26
Xanthoma
- Most often associated with hypercholesterolemia
- Characterized by yellowish papules or nodules composed of focal dermal collections of lipid-laden histiocytes
- Occurs most frequently on the eyelids
27
Hemangioma
- Capillary hemangioma: small, blood-filled capillaries lined with a single layer of endothelium
(1) Port-wine stain - purple-red area on the face or neck
(2) Strawberry hemangioma - bright-red raised lesion
(3) Chery hemangioma - small, domed-shaped red papule
- Cavernous hemangioma: large, endothelium-lined spaces in the dermis and subdermis
28
Squamous cell carcinoma (skin)
- Common malignant skin tumor
- Most often locally invasive; fewer than 5% of tumors metastasize
- Associated most often with excessive exposure to sunlight
- Other risk factors: albinism, xeroderma pigmentosum, immunosuppressive therapy, arsenic poisoning, chronic inflammation
- Usually involves sun-exposed areas - face and back of hands, lower part of face - lower lip
- Presents as scaling, indurated, ulcerated nodule
- Invasion of dermis by sheets and islands of neoplastic epidermal cells, often with keratin "pearls", is characteristic
29
Basal cell carcinoma (skin)
- Most common of all malignant skin tumors
- Risk factors: exposure to sunlight (UVB), albinism, and xeroderma pigmentosum
- Presents as pearly papule, often with overlying telangiectatic vessels
- Characterized by clusters of darkly staining basaloid cells with a typical palisade arrangement of the nuclei of the cells at the periphery of the tumor cell clusters
- Tends to involve the upper part of face - upper lip
- Can be locally aggressive, ulcerate, and bleed
- Matastasis is rare
30
Malignant melanoma
- Malignant neoplasm of melanocytes
- Most common cause of death from skin cancer
- Risk factors: exposure to sunlight, albinism, xeroderma pigmentosum
- Recognized as mole-like growth with 'ABCD': Asymmetry, Borders are irregular, Color is not uniform, Diameter>6mm
- Characterized by two growth phases:
* Radial growth horizontally along epidermis and superficial dermis
* Vertical growth into deep dermis (higher risk of metastasis)
- Four major subtypes of melanoma:
(1) Lentigo maligna melanoma - radial growth
(2) Superficial spreading melanoma - most common subtype, radial growth
(3) Nodular melanoma - vertical growth, push the epidermis up; poorest prognosis of the subtypes
(4) Acral-lentiginous melanoma - arises on palms or soles, often i dark-skinned persons. Not related to UV-light exposure
31
Dermatomyositis
- Skin and muscle inflammatory disorder
- Skin rash - liliac discoloration of the upper eyelids with periorbital edema
- Grotton lesions - scaling red patches over the knuckles, elbows, knees
- Muscle weakness (proximal parts)
- Interstial lung disease, dysphagia, vasculitis, etc.
- 40% of adult patients have cancer
