DD Cutaneous Infxns and Infestations

Question 1

Anti-microbial peptides:

Answer 1

Alpha-defensins (hNP1, hNP2),
beta-defensins (hBD-1,-2,-3)
Cathelicidin (hCAP-18)
Psoriasin and RNase7

Question 2

What smear do you use to dx HSV and VZV?

Answer 2

Tzanck preparation (smear - look for multinucelated keratinocytes and large vesicular nuclei in keratinocytes),

Question 3

Honey-colored crust

dx?

Answer 3

Non bullous impetigo most likely caused by
strep since it is non bullous (maybe staph)

• If bullous impetigo then suspect Staph aureus (scalded skin)

Question 4

Who is at increased susceptibility of getting cellulitis?

Answer 4

very young, old, immunocompromised, IV drug users, pts w/chronic ulcers.

Question 5

Cliff drop border

Answer 5

St. Anthony’s fire

–> Erysipelas

Question 6

Cellulitis

Answer 6

primary lesion is tender, illdefined area, erthematous, painful, variable lymphadenopathy, streaking.

Question 7

Hunterian Chancre

Answer 7

Papule breaks down to ulcer -->
Non- tender ulcer
Indurated (hardening)
Heals 3-6 weeks
Lymphadenopathy

• Dx syphilis

Question 8

KOH exam to look for what?

Answer 8

Hyphae of arthrospores

indicating fungal infxn - ie dermatophyte, candidiasis

Question 9

Food source of Tinea Versicolor

Answer 9

follicular lipids

Question 10

Tinea (Pityriasis) Versicolor show as hypopigmented patches bc?

Answer 10

production of azelaic acid that inhibits function of tyrosine produced by melanocytes.

Question 11

Scabies life cycle

Answer 11

30 day lifecycle w/ female laying down 60 to 90 eggs that mature in approximately 10 days.

Question 12

Scabies vs lice?

Answer 12

You cant see scabies: look for nodules/burrows or use microscope

Lice: tan-brown, 6 legs