Dermatopathology

Question 1

Histopathological features of classic lichen planus

Answer 1

• confluent orthokeratosis without parakeratosis
• wedge shaped hypergranulosis
• epidermal acnathosis with saw-toothed rete ridges
• band-like lymphocytic infiltrate in the superficial dermis
• vacuolar degeneration of basal keratinocytes with necrotic keratinocytes in epidermis (Civatte bodies) and papillary dermis (colloid bodies)

Question 2

Name 4 histopathological variants of lichen planus

Answer 2

1. Bullous lichen planus
2. Hypertrophic lichen planus
3. Lichen planopilaris
4. Atrophic lichen planus

Question 3

What are the immunofluorescence findings of lichen planus?

Answer 3

• Colloid bodies stain with IgM, occasionally with IgG, IgA and C3
• Fibrinogen deposits are apparent at the dermoepidermal junction

Question 4

List the types, timing, and histopathological manifestations of cutaneous GVHD

Answer 4

• Acute
  
  • Onset: withing first 3 months posttransplant (can be recurrent)
  • Micro: vacuolar interface dermatitis
• Chronic (lichenoid)
  
  • Onset: Greater than 3 months posttransplant (often follows acute GVHD).
  • Micro: Lichenoid interface dermatitis
• Chronic (sclerodermoid)
  
  • Onset: Upt to 18 months posttransplant
  • Micro: morphea-like fibrosing dermatitis

Question 5

Although not universally applied, what is the grading scheme for GVHD?

Answer 5

• Grade 1: basal vacuolar change
• Grade 2: dyskeratotic keratinocytes; some associated with lymphocytes (satellite cell necrosis)
• Grade 3: subepidermal cleft and microvesicle formation
• Grade 4: dermoepidermal split =/- epidermal necrosis

Question 6

What causes erythema multiforme?

Answer 6

variety of triggers have been implicated in the development of erythema multiforme, most commonly:

• Infections (esp HSV, but also mycoplasma pneumoniae
• Drugs (e.g., NSAIDS)

Question 7

What are the histopathological findings in erythema multiforme?

Answer 7

• Early form: characterized by a vacuolar interface dermatitis - lymphocytes obsucring the dermoepidermal junction with vacuolar degernation and necrosis/apoptosis of keratinocytes
• More advanced form: characterized by bullous lesions with subepidermal vesiculation
• Severe forms: resemble toxic epidermal necrolysis with marked epidermal necrosis

Question 8

What histochemical stains may be useful in the diagnosis of lupus?

Answer 8

• Stains to highlight increased dermal mucin (e.g., alcian blue, colloidal iron)
• Stains to highlight basement membrane thickening (e.g,, PAS)

Question 9

What is a “lupus band” and what is the significance and diagnostic value?

Answer 9

• Variants of cutenous lupus erythematosus that involve the dermoepidermal junction may exhibit a “lupus band” (IgG and/or IgM and/or C3) on direct IF
• Incidence of positivity is related to lesion site and duration
• the lupus band test has a high incidence of positivity in SLE, in both lesional and onlesional sun-exposed skin
• it has a lower incidence of positivity in SLE if nonlesional sun-portected skin is sampled
• It may be falsely positive in chronically sun-exposed skin of normal ocntrals (up to 30% of cases)

Question 10

A clinician calls you about a patient with a bullous diase. What advice should you give about the site of the biopsy and the gransport medium to use?

Answer 10

• specify lesional skin four routine sections and perilesional skin for IF
• Specify formalin fixation for the “routine sample” and Michel’s transport medium for the “IF sample”
• If the disease is focal, a save biopsy (to include the whole bislter amy be preferable to a punch biopsy for routine histopathology.

Question 11

How are the vesiculobullous diseases classified?

(based on 3 features)

Answer 11

1. Location of the split (subpepidermal, intraepidermal)
2. Mechanism of the split (intraepidermal spongiosis, acantholysis, ballooning)
3. Presence or absence of dermal inflammatory infiltrate and compisiton

Question 12

Pemphigus vulgaris

(clinical features, micro, IF, other)

Answer 12

• Clinical features:
  
  • middle-aged adults, cutaneous and oral involvement
  • Fragile blisters that can be induced by rubbing normal skin (nikolsky sign)
• Micro:
  
  • suprabasal acantholysis with retaine dlining (“tomb stoning”) of basal keratinocytes
  • broad zone of acantholysis with involvement of follicular epithelium
  • mild mixed infiltrate
• IF:
  
  • DIF: net-like or intracellular IgG +/- C3
• Other:
  
  • target antigen: desmoglein 3 (most common) and desmoglein 1

Question 13

Hailey-Hailey disease

• benign familiar pemphigus -

(clinical, micro, IF, other)

Answer 13

• Clinical
  
  • AD genodermatosis, 2nd-4th decade of life
  • Vesicles, erosions and crusted lesions of mostly flexural skin
• Micro
  
  • acantholysis in a “dilapidated brick wall” pattern
  • minimal dyskeratosis
  • Adnexal epithelium spared
• IF - NEGATIVE
• Other
  
  • Mutation of TP2C1 (3q21-q24)

Question 14

Name 4 disorders characterized by intraepideraml acantholysis

Answer 14

1. Pemphigus vulgaris
2. Hailey-Hailey disease
3. Darier disease
4. Grover disease