Skin Pathology Flashcards

1
Q

Characteristics of Vitiligo

A

Irregular, completely depigmented skin patches

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2
Q

Characteristics of Melasma

A

Irregular blotchy patches of hyperpigmentation on the face .

It is associated with sun exposure, oral contraceptive use and pregnancy

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3
Q

Characteristics of Freckles

A

Light brown macules on the face, shoulders and chest.

They are common in fair-skinned children and tend to darken and fade with the seasons due to sunlight exposure

Microscopically, freckles are characterized by increased melanin deposition in the basal cell layer of the epidermis with a normal number of melanocytes

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4
Q

Characteristics of Benign lentigo

A

Localized proliferation of melanocytes which cause small, oval, light brown macules

Microscopically, benign lentigos show linear melanocyte hyperplasia

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5
Q

Characteristics of Congenital nevi (birthmark)

A

Present at birth; giant congenital nevi have increased risk of developing ,melanoma

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6
Q

Characteristics of Nevocellular nevus (mole)

A

Benign tumor of melanocytes that is releated to sun exposure

Types of nevi include junctional compound and intradermal.

Nevi have uniform tan to brown color with sharp well-circumscribed borders and tend to be stable in shape and size

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7
Q

Characteristics of Dysplastic nevi (mole)

A

Larger and more irregular than common nevi and they may have pigment variation

Dysplastic nevus syndrome is autosomal dominant (CMM1 locus on chromosome 1) patients often have multiple dysplastic nevi

There is an increased risk of developing melanoma

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8
Q

Characteristics of Malignant melanoma

A

Malignancy of melanocytes whose incidence is increasing at a rapid rate with peak in ages 40-70

Risk factors include chronic sun exposure, sunburn, fair skin, dysplastic nevi syndrome, and familial melanoma

Melanomas characteristically form skin lesions of large diameter with asymmetric and irregular borders and variegated color

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9
Q

What causes malignant melanoma?

A

Loss of function mutation of the p16 tumor supressor gene

CDKN2A on chromosome 9

Somatic mutations of NRAS and BRAF

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10
Q

Characteristics of lentigo melanoma

A

Usually located on the face or neck of older individuals and has the best prognosis

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11
Q

Characteristics of superficial spreading melanoma

A

Most common type of melanoma and has a primarily horizontal growth pattern

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12
Q

Characteristics of acral lentiginous melanoma

A

Most common melanoma in dark-skinned individuals, it affects palms, soles and subungual area

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13
Q

Characteristics of nodular melanoma

A

Nodular tumor with a vertical growth pattern that has the worst prognosis of the melanoma

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14
Q

How is the prognosis of melanomas determined?

A

Determined by TNM staging

T status is based on the depth of invasion (Breslow thickness measured histologically in millimeters)

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15
Q

Characteristics of Acanthosis nigricans

A

Thickened, hyperpigmented skin of posterior neck, axillae, and groin

It is often associated with obesity and hyperinsulinism

On rare occasions it is associated with internal malignancy (stomach and other GI malignancies)

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16
Q

Characteristics of Seborrheic keratoses

A

Benign squamoproliferative neoplasms that are very common in middle-aged and elderly individuals

They may occur on the trunk, head, neck and the extremities

The lesions are tan to brown coin-shaped plaques that have a granular surface with a “stuck on” appearance

Characterized microscopically by basaloid epidermal hyperplasia and “horn cysts”

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17
Q

What is the sign of Leser-Trelat?

A

Associated with seborrheic keratoses

It is a paraneoplastic syndrome with the sudden development of multiple lesions which may accompany internal malignancy

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18
Q

Characteristics of Psoriasis

A

Autoimmune disorder with a clear genetic component that causes increased proliferation and turnover of epidermal keratinocytes

Common sites of involvement include the knees, elbows, and scalp; the classic skin lesion is a well demarcated erythematous plague with a silvery scale.

Removal of scale results in pinpoint bleeding (Auspitz sign)

Nail beds show pitting and discoloration

Common form is psoriasis vulgaris

19
Q

Characteristics of pemphigus

A

Rare, potentially fatal autoimmune disorder that is characterized by intraepidermal blister formation

Autoantibodies directed against desmoglein 3 in keratinocyte desmosome, with resulting loss of intercellular adhesion (acantholysis) and blister formation

Microscopic examination shows intaepidermal acantholysis which leaves behind a basal layer of keratinocytes, which has a tombstone-like arrangment

Immunofluorence shows a net-like pattern of IgG staining between the epidermal keratinocytes that cause bullae

20
Q

Characteristics of Bullous pemphigoid

A

Relatively common autoimmune disorder of older individuals characterized by subepidermal blister formation with tense bullae that do no rupture easily

The condition results from production of autoantibodies directed against keratinocyte hemidesmosome called bullous pemphigoid antigens 1 and 2

Immunoflorence shows linear deposits of IgG at the dermal-epidermal junction

21
Q

Characteristics of Dermatitis herpetiformis

A

Rare immune disorder that is often associated with celiac sprue

Characterized by epidermal blister formation with itchy, grouped vesicles and occasional bullae on the extensor surfaces.

Production of IgA antibodies directed against gliadin and other antigens deposit in the tips of the dermal papillae and result in subepidermal blister formation

Immunoflorence shows granular IgA deposits at the tips of the dermal papillae

22
Q

Characteristics of Porphyria cutanea tarda

A

Acquired and familial disorder of heme synthesis

Patients experience upper extremity blistering secondary to sun exposure and minor trauma

Microscopically, there are subepidermal blisters with minimal inflammation

Direct immunoflorences shows deposition of immunoglobulins and complement at the epidermal basement membrane and around dermal vessels

23
Q

Characteristics of ichtyosis vulgaris

A

Common inherited (AD) skin disorder characterized by a thickened stratum corneum with absent stratum granulosum onset is in childhood.

Patients have hyperkeratotic, dry skin on the trunk and extensor surfaces of limb areas

24
Q

Characteristics of xerosis

A

Common cause of pruritus and dry skin in the elderly that is due to decreased skin lipids

Cancer patients receiving epidermal growth factor receptor inhibitor are susceptible

Treatment is with emollients

25
Q

Characteristics of eczema

A

Group of inflammatory skin diseases characterized by pruritius and epidermal spongiosis (edema)

26
Q

Characteristics of acute eczema

A

Vesicular and erythematous rash

27
Q

Characteristics of chronic eczema

A

Develops following repetitive scratching and is characterized by dry, thickened, hyperkeratotic skin

28
Q

Characteristics of atopic dermatitis

A

Defects in the keratinocyte barrier are due to mutations in the filaggrin gene (FLG)

29
Q

Characteristics of contact dermatitis

A

Either allergic type or photodermatitis type

30
Q

Characteristics of polymorphous light eruption

A

Most common idiopathic form of photocermatosis and causes pruritic erythematous macules, papules, plaques or vesicles on exposure to sunlight

There is dermal edema and inflammation

31
Q

Characteristics of verrucas (warts)

A

Caused by human papillomavirus.

Verruca vulgaris is the most common type

32
Q

Characteristics of cutaneous lupus erythematosus

A

May be acute (facial butterfly rash), subacute (photosensitive rash on anterior chest, upper back, and upper extremities), or chronic (discoid plagues, usually above the neck)

33
Q

Characteristics of erythema multiforme

A

Hypersensitivity skin reaction to infections or drugs.

Characterized by vesicles, bullar, and “targetoid” erythematous lesions.

34
Q

Characteristics of Stevens-Johnson syndrome

A

Severe form of erythema multiforme.

Has extensive involvement of skin and mucous membranes

35
Q

Characteristics of pityriasis rosea

A

Pruritic rash that starts with an oval-shaped “herald patch” and progresses to a papular eruption of the trunk to produce a “Christmas tree” distribution

It is clinically diagnosed, self-limiting and possibly a viral exanthem

36
Q

Characteristics of granuloma annulare

A

Chronic inflammatory disorder that causes papules and plaques.

Palisaded granulomas are present microscopically

37
Q

Characteristics of erythema nodosum

A

Raised, erythematous, painful nodules of subcutaneous adipose tissue, typically on the anterior shins, which can be associated with granulomatous disease and streptococcal infection

38
Q

Characteristics of epidermoid cyst

A

Common benign skin cyst lined with stratified squamous epithelium and filled with keratin debris

39
Q

Characteristics of actinic keratosis

A

Sun-induced dysplasia of the keratinocytes that causes rough, red papules on the face, arms and hands

40
Q

Characteristics of squamous cell carcinoma (SCC)

A

Peak incidence at age 60.

Risk factors include chronic sun exposure (UVB), fair complexion, chronic skin ulcers or sinus tracts, long-term exposure to hydrocarbons, arsenic, burns, and radiation; immunosupression and xeroderma pigmentosum

Actinic keratosis and Bowen disease are precursors

Occurs on sun-exposed areas and causes a tan nodular mass which commonly ulcerates

Microscopic examination shows nest of atypical keratinocytes that invade dermis, often times formation of keratin pearls, and intracellular bridges (desmosomes) between tumor cells

41
Q

What are the common mutations that cause SCC?

A

TP53 and HRAS

42
Q

Characteristics of keratoacanthoma

A

Well differentiated squamous cell carcinoma which grows rapidly, dome-shaped nodules with a central keratinofilled crater; these are often self-limited and may regress spontaneously

43
Q

Characteristics of basal cell carcinoma (BCC)

A

Most common tumor in adults in the western world; it is most common in middle-aged or elderly individuals and arises from the basal cells of hair follicles

Risk factors include chronic sun exposure, fair complexion, immunosuppression and xeroderma pigmentosum

Occurs on sun exposed, hair bearing areas (face), may form pearly papules; nodules with heaped-up, translucent borders, telangiectasia, or ulcers (rodent ulcer)

Microscopically shows invasive nests of basaloid cells with a palisading growth pattern