DIT review - MSK 3 Flashcards
Describe histologic features of psoriasis
- 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)
Describe gross appearance of seborrheic keratosis
- Raised, discolored plaques that have a coin-like, “waxy/greasy” appearance
- “Stuck on”
Describe histology of seborrheic keratosis
Keratin pseudocysts
What is Lesser-Trelat sign
- multiple seborrheic keratosis appearing suddenly
- Suggestive of GI malignancy
Describe defect behind albinism
- 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
Describe defect behind vitiligo
Localized loss of skin pigment due to autoimmune destruction of melanocytes
What are pathogens that cause impetigo
- Superficial bacterial skin infection
- Usually due to Staph aureus or Strep pyogenes
- Honey-colored crusting
What is Erysipelas
- Infection involving upper dermis and superficial lymphatics
- Usually from Strep pyogenes
- Well-define demarcation between infected and normal skin
Pathogens and skin layers involved in cellulitis
- Acute, painful spreading of infection to deeper dermis and subcutaneous tissue
- Usually from Strep pyogenes or staph aureus
In what skin disorder do you see crepitus
Necrotizing fasciitis
- Results in crepitus from the methane and CO2 production
In what skin layer does epidermolysis occur in staph scalded skin syndrome
- Results in epidermolysis of stratum granulosum
- Leads to sloughing of skin (+Nikolsky sign)
What pathogen is the cause of hairy leukoplakia
Ebstein Barr virus (EBV)
What is seen on histology in molluscum contagiosum
- Cytoplasmic inclusions within keratinocytes (molluscum bodies)
Describe histology of pemphigys vulgaris
- Acantholysis of stratum spinosum
- Basal layer remains attached = “tombstone” appearance
Describe immunofluorescence of pemphigus vulgaris
- Immunofluorescence will have a fish net appearance à IgG and C3 deposits in a “chicken wire” pattern
What is the defect in dermatitis herpetiformis
- Deposits of IgA at tips of dermal papillae