DIT review - MSK 3

Question 1

Describe histologic features of psoriasis

Answer 1

• Acanthosis (epidermal hyperplasia)
• Increase in stratum spinosum and decrease in stratum granulosum
• Parakeratosis (hyperkeratosis with retention of keratinocyte nuclei in the stratum corneum)
• Munro microabscesses (neutrophils within the stratum corneum)
• Auspitz sign (pinpoint bleeding due to thinning of epidermis above elongated dermal papilla)

Question 2

Describe gross appearance of seborrheic keratosis

Answer 2

• Raised, discolored plaques that have a coin-like, “waxy/greasy” appearance
  
  • “Stuck on”

Question 3

Describe histology of seborrheic keratosis

Answer 3

Keratin pseudocysts

Question 4

What is Lesser-Trelat sign

Answer 4

• multiple seborrheic keratosis appearing suddenly
  
  • Suggestive of GI malignancy

Question 5

Describe defect behind albinism

Answer 5

• Congenital lack of pigment due to enzyme defect (e.g. tyrosinase) that impairs melanin production
• Normal melanocyte number with decreased melanin production
• Increased risk of skin cancer

Question 6

Describe defect behind vitiligo

Answer 6

Localized loss of skin pigment due to autoimmune destruction of melanocytes

Question 7

What are pathogens that cause impetigo

Answer 7

• Superficial bacterial skin infection
• Usually due to Staph aureus or Strep pyogenes
• Honey-colored crusting

Question 8

What is Erysipelas

Answer 8

• Infection involving upper dermis and superficial lymphatics
• Usually from Strep pyogenes
• Well-define demarcation between infected and normal skin

Question 9

Pathogens and skin layers involved in cellulitis

Answer 9

• Acute, painful spreading of infection to deeper dermis and subcutaneous tissue
• Usually from Strep pyogenes or staph aureus

Question 10

In what skin disorder do you see crepitus

Answer 10

Necrotizing fasciitis

• Results in crepitus from the methane and CO2 production

Question 11

In what skin layer does epidermolysis occur in staph scalded skin syndrome

Answer 11

• Results in epidermolysis of stratum granulosum
• Leads to sloughing of skin (+Nikolsky sign)

Question 12

What pathogen is the cause of hairy leukoplakia

Answer 12

Ebstein Barr virus (EBV)

Question 13

What is seen on histology in molluscum contagiosum

Answer 13

• Cytoplasmic inclusions within keratinocytes (molluscum bodies)

Question 14

Describe histology of pemphigys vulgaris

Answer 14

• Acantholysis of stratum spinosum
• Basal layer remains attached = “tombstone” appearance

Question 15

Describe immunofluorescence of pemphigus vulgaris

Answer 15

• Immunofluorescence will have a fish net appearance à IgG and C3 deposits in a “chicken wire” pattern

Question 16

What is the defect in dermatitis herpetiformis

Answer 16

• Deposits of IgA at tips of dermal papillae

Question 17

Presentation and disease associated with dermatitis herpetiformis

Answer 17

• Pruritic papules, vesicles, and bullae (often found on elbow)
• Associated with Celiac disease

Question 18

What layer of the skin is seperated in SJS?

Answer 18

Epidermal-dermal junction

Question 19

Classic presenation of SJS?

Answer 19

• Fever, bullae, necrosis, targetoid lesions
• Sloughing of skin at epidermal-dermal junction
• Usually 2 mucus membranes involved

Question 20

Drugs that cause SJS?

Answer 20

• Seizure medications (Ethosuximide, Carbamazepine, Lamotrigine, Phenytoin, Phenobarbitol)
• Sulfa medication
• Penicillin
• Allopurinol

Question 21

What defines Toxic epidermal necrolysis (TEN)

Answer 21

More severe form of Stevens-Johnson that involves >30% of body surface

Question 22

Describe presentation of Lichen planus

Answer 22

• 6 P’s = pruritic, purple, polygonal, planar, papules and plaques
• Wickham striae (reticular white lines) = mucosal involvement
• Think of a witch (idk why Lichen makes me think of witches)
  
  • Witches wear purple and have a bunch of warts – 6 Ps
  • Wicken = Wickham striae

Question 23

Histology of Lichen planus

Answer 23

• Inflammation of dermal-epidermal junction
• Saw-tooth appearance
  
  • Witches torture people = sawtooth

Question 24

What are hyperkeratotic scaly plaque, often appearing on face, back, or neck

Precursor to squamous cell carcinoma

Answer 24

Actinic keratosis

Question 25

What epidermal layer is especially hyperplastic in acanthosis nigracans?

Answer 25

statrum spinosum (definition of acanthosis is increased stratum spinosum)

Question 26

Common causes of erythema nodosum

Answer 26

* Painful inflammatory disorder of subcutaneous fat, usually on anterior shins * Associated with sarcoidosis, coccidioidomycosis, histoplasmosis, TB, strep, leprosy, IBD

Question 27

What is pityriasis rosea

Answer 27

* Initial lesion (“herald patch”) followed by scaly erythematous plaques in a “Christmas tree” distribution on trunk * Self-resolving in 6-8 weeks

Question 28

What other disease is associated with Lichen planus

Answer 28

hepatitis C

Question 30

What is the most common skin cancer?

Answer 30

Basal cell carcinoma

Question 31

What skin cancer is most likely to be malignant?

Answer 31

Melanoma

Question 32

What tumor presents with nodules of cells with peripheral palisading?

Answer 32

Basal cell carcinoma

Question 33

Describe gross appearance of basal cell carcinoma

Answer 33

* Elevated nodule with central, ulcerated crater with rolled borders surrounded by dilated vessels (telangiectasias) = “pink, pearl-like papule”

Question 34

What carcinoma appears on lower lip vs. upper lip

Answer 34

THINK: This is BS: * B = basal cell upper lip * S = squamous cell lower lip

Question 35

Histology of squamous cell carcinoma

Answer 35

Keratin pearls

Question 36

What is keratocanthoma

Answer 36

well-differentiated squamous cell carcinoma that develops rapidly and regresses spontaneously

Question 37

Mutation commonly associated with melanoma

Answer 37

BRAF kinase mutation

Question 38

What are the ABCDEs of melanoma

Answer 38

* Asymmetry, border irregularity, color variation, diameter \> 6 mm, evolution

Question 39

Tumor marker of melanocytes

Answer 39

* S-100 tumor marker (neural crest cell marker)

Question 40

Radial vs. Vertical growth of melanoma

Answer 40

* Radial growth * Horizontal growth along epidermis and superficial dermis * Low risk of metastasis * Vertical growth * Into deep dermis * Increases risk of metastasis * Breslow thickness is most important prognostic factor

Question 41

Treatment for melanoma

Answer 41

* Vemurafenib for patients with BRAF V600E mutation