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USMLE Step 1 Prep > First Aid: Dermatology > Flashcards

First Aid: Dermatology Flashcards

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USMLE® Step 1 flashcards
1
Q

Name the epidermis layers from surface to base

A

Californians Like Girls in String Bikinis

Stratum Corneum (keratin)
Stratum Lucidum
Stratum Granulosum
Stratum Spinosum (spines=desmosomes)
Stratum Basale (stem cell site)
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2
Q

What novel cell property/feature would develop with the loss of Adherens junction?

A

Loss of E-Cadherins promote metastasis

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3
Q

What disorder would develop with autoantibodies directed at desmosomes? Which skin layer would this affect?

What disorder would develop with autoantibodies directed at hemidesmosomes? Which skin layer?

A

Pemphigus Vulgaris - Stratum Spinosome (spines = desmosomes)

Bullous Pemphigoid (“down bullow”) - Stratum Basale, which connects keratin in basal cells to underlying basement membrane

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4
Q

What destructive process leads to Vitiligo?

How is this disease evident in lighter skin individuals?

A

Autoimmune destruction of melanocytes

After long periods in the sun, there are patches of skin where no tanning has occurred.

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5
Q

What is Melasma (chloasma)?

A

Hyperpigmentation associated with pregnancy or OCP use (mask of pregnancy)

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6
Q

What are two possible causes of albinism? What would be the difference in the number of melanocytes between two twins (one albino and one normal)?

A
  1. Decreased melanin production from tyrosine kinase defect or tyrosine transport defect
  2. Failure of neural crest cell migration during development
    - No difference, SAME # of melanocytes, just less melanin in Albino
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7
Q

Describe the process that leads to pigmentation of skin.

A

Melanocytes at the basal membrane of the epidermis convert tyrosine into melanin within Melanosomes.

Melanosomes store the melanin and are transferred into keratinocytes of the epidermis.

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8
Q

What disease presents with hyperkeratosis, parakeratosis and acanthosis?

A

Psoriasis

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9
Q

A patient presents with erythematous, pruritic eruptions on her antecubital fossa. She has a history of asthma. What may be the cause for disease?

What if a patient had the same symptoms as above, but suffered from a Type IV hypersensitivity reaction. What could be the causes for this?

A
  1. Atopic Dermatitis (Eczema)

2. Contact Dermatitis from poison ivy, nickel jewelry, chemicals (detergent), drugs (penicillin)

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10
Q

A patient presents with comedones and pustules covering her face and back. Upon closer inspection you also notice nodules dispersed throughout. What could be the cause for this and what can you use to treat this patient?

A

Acne Vulgaris - from chronic P. Acnes infection and inflammation of hair follicles and sebaceous glands

Tx: Benzoyl Peroxide or Vitamin A derivatives (isotretinoin)

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11
Q

A patient presents with well circumscribed, salmon-colored plaques and silvery scales. The lesions are mostly on the knees and elbows, but you also notice lesions on the scalp and pitting of the nails. Some of the plaques have pinpoint bleeds on them. What characteristic feature would be seen on histology and what are possible treatments for this?

A

Psoriasis - from excessive keratinocyte proliferation

Histo: Monroe microabcesses (PMNs in stratum corneum)

Tx: Corticosteroids, immune modulating therapy, PUVA (Psoralen + UVa light)

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12
Q

A 50 year old male, former healthcare worker, presents with pruritic papules and plaques on his wrist and elbows. The lesions are flat and polygonal in shape, and purple in color. You notice reticular white lines on the oral mucosa (Whickham Striae). What would you see on histology, and what may be associated with this disorder?

A

Lichen Planus

Histo: Inflammation of dermal/epidermal junction –> Sawtooth appearance

Associated with Hepatitis C chronic infection

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13
Q

A 45 year old female presents with flaccid bullae on her chest and breasts. Many of these lesions have burst and are crusty and moist. You also notice similar lesions in the oral mucosa. IF reveals antibodies around keratinocytes in a “net-like” pattern, and the epidermis separates upon manual stroking (+ Nikolsky sign). What is the underlying cause of this disorder?

A

Pemphigus Vulgaris - Autoimmune disorder with IgG Abs against desmoglein of desmosomes

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14
Q

Describe the key differences that will allow you to differentiate Bullous Pemphigoid from pemphigus vulgaris.

A

IgG against hemidesmosomes –> IF reveals linear pattern at dermal-epidermal jct.

Tense blisters that do not rupture easily

Blisters spare oral mucosa

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15
Q

A 20 year old patient of Scandanavian descent presents with pruritic papules, vesicles and bullae on her arms, and especially on the elbow. IF reveals Abs to IgA at the tips of the dermal papillae. She also complains of diarrhea and weakness. What could be a simple treatment to cure her of these lesions?

A

Dermatitis Herpetiformis associated with Celiac Sprue

Tx: Restrict gluten in the diet

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16
Q

A 24 year old sexually active male presents with target shaped lesions and bullae on his hand and fingers. What could be a key factor in this disease progression? Other possibilities?

A

Erythema Multiforme - probably from HSV infection (also could be from Mycoplasma pneumoniae, penicillin, sulfa drugs, lupus, cancer)

17
Q

An 8 year old boy presents following a recent infection, with fever and bullae formation. You notice target shaped lesions at the corner of the eyes and mouth. After some time there is diffuse sloughing of large swaths of skin over many areas of the body. What caused these pathologies?

A

Stevens-Johnson syndrome from an adverse drug reaction –> became Toxic epidermal necrolysis

Rx causes, antibiotics and sulfa drugs

18
Q

An elderly patient presents with raised, pigmented plaques on the extremeties and face. The lesions are flat and greasy in appearance, and have a stuck on appearance. The patient reports that these appeared suddenly in the past week or so. What do you want to check for?

A

Seborrheic Keratosis - squamous eptihelial proliferation w/ keratin filled cysts

Leser-Trelat sign - Check for underlying malignancy (especially CA of GI tract, or lymphoid)

19
Q

A patient presents with thick, velvity dark skin on the neck and axilla. What underlying disease could causes this?

A

Hyperinsulinemia (diabetes, obesity, Cushing syndrome)

Visceral Malignancy (gastric adenocarcinoma)

20
Q

A 70 year old woman presents with raised pink, pearly nodules on the upper lip. The lesion has rolled borders with a central ulceration, and telangiectasias. What would you notice on histology?

A

Basal Cell Carcinoma - #1 skin cancer and it is on sun exposed areas; good prognosis

Histo: Nodules of basal cells with peripheral palisading nuclei

21
Q

What are 3 major risk factors for skin cancer?

A
  1. Increased exposure to UVB sunlight
  2. Xeroderma Pigmentosum
  3. Albinism
22
Q

A 57 year old woman with a history of kidney transplant presents with a red ulcerative nodular mass on her lower lip. Histology reveals keratin pearls. What are some possible precursors to this lesion?

A

Squamous Cell Carcinoma

  1. Actinic Keratosis - scaly plaque
  2. Keratoacanthoma - grows rapidly (4-6 weeks) and regresses spontaneously over months
23
Q

What are the 5 characteristic features of a melanoma, and what tumor marker can distinguish it?

A 
Asymmetry
Border irregularity
Color Variation
Diameter >6mm
Evolution over time

S-100 tumor marker

24
Q

A patient has a metastatic and unresectable melanoma. They also have a BRAF V600E mutation. What treatment may benefit this patient?

A

Vemurafenib, a BRAF kinase inhibitor

25
Q

What are the 4 subtypes of melanoma, and their prognosis?

A
  1. Lentigo Maligna Melanoma - horizontal growth along E/D jct. - good prognosis
  2. Superficial Spreading - #1 subtype w/ dominant early radial phase - good prognosis
  3. Nodular - early vertical phase - poor prognosis
  4. Acral Lentiginous - Palms and soles of dark skinned people - unrelated to UVB`
26
Q

A patient presents with pruritic wheals. Histology reveals mild, superficial infiltrate composed of mononuclear cells and occasional eosinophils around the dermal venules. What lead to this lesion and how is it characterized?

A

Urticaria (Hives) –> secondary to antigen induced granulation of focal mast cells via IgE antibody sensitization

-Characterized by lymphatic channel dilation and superficial dermal edema

27
Q

A 6 y/o patient presents with erythematous macules and pustules on the face. The lesions form erosions with a dry honey colored crust. What is the infective agent, and what level of the skin is affected?

A

Impetigo - very superficial skin infection from S.Aureus or S.pyogenes

28
Q

A 2 y/o boy presents with red, tender and swollen rash on his lower extremity. He has a fever, and the mother thinks he may have been bitten by something while playing in their garden. What is the causative agent in this disorder and what major problem do you want to avoid?

A

Cellulitis - acute infection of dermis and subcutaneous tissue usually from S. pyogenes or S. Aureus

-Could progress to necrotizing fasciitis

29
Q

What key symptomatic features indicate necrotizing fasciitis?

A
  1. Crepitus - from methane and CO2 production

2. Bullae and purple color to skin

30
Q

A 3 year old girl presents with fever and a generalized erythematous rash on her phase. You notice large amounts of skin sloughing off from this region. Over time it heals completely. What area of skin is being affected and by what pathological agents?

A

Staph Scalded Skin Syndrome - Exfoliating A/B toxins lysing of skin at stratum granulosum

31
Q

What is the more sever form of Staph scalded skin syndrome?

A

Toxic Epidermal Necrolysis - Massive sloughing of skin, separating at dermal/epidermal junction

32
Q

An HIV + patient presents with white, painless plaques on the tongue, which cannot be scraped off. What mediates this lesion’s formation?

A

Hairy Leukoplakia - EBV mediated

33
Q

A 20 year old sexually active male presents with soft tan-colored cauliflower-like papules on his fingers. What caused this disorder?

A

Verrucae - warts caused by HPV

34
Q

A 24 year old sexually active female presents with firm, pink umbilicated papules on her vulva. A biopsy is taken. What would be seen on histology and what is the cause of this?

A

Molluscum Contagiosum - Poxvirus

Histo: Molluscum bodies (viral inclusions) w/in keratinocytes

35
Q

A 34 year old woman with a history of Crohn’s disease presents with painful red lesions on her anterior shins. What is the cause of this?

A

Erythema Nodosum - inflammatory lesions of subQ fat

36
Q

A patient presents with multiple plaques with collarette scale in a christmas tree distribution on his back. The patient noticed some red patches on his neck a few days ago but thought nothing of it. What treatment should be provided?

A

Pityriasis rosea - self-resolving in 6-8 weeks

37
Q

A patient presents with cutaneous lesions on the eyelid. Microscopy reveals lipid-laden macrophages. What may this be associated with?

A

Xanthelasma is the lession

Assoc. with Primary Biliary Cirrhosis

USMLE Step 1 Prep (11 decks)

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