ABD Dermatopathology 2 — Questions and Answers
Question 1: A skin biopsy shows a 'sawtooth' pattern of the rete ridges with a band-like lymphocytic infiltrate at the dermoepidermal junction. What is the diagnosis?
- Lichen planus (Correct answer)
- Psoriasis
- Discoid lupus erythematosus
- Pityriasis rosea
Correct answer: Lichen planus
Sawtooth rete ridges with a band-like (lichenoid) interface lymphocytic infiltrate are classic for lichen planus.
Question 2: Munro microabscesses (collections of neutrophils in the stratum corneum) are a characteristic histologic feature of which condition?
- Psoriasis (Correct answer)
- Eczema
- Bullous pemphigoid
- Dermatophytosis
Correct answer: Psoriasis
Munro microabscesses in the parakeratotic cornified layer are a hallmark of psoriasis.
Question 3: A pigmented lesion demonstrates nests of melanocytes at both the dermoepidermal junction and within the dermis. This architecture defines which nevus type?
- Compound nevus (Correct answer)
- Junctional nevus
- Intradermal nevus
- Blue nevus
Correct answer: Compound nevus
A compound nevus has melanocytic nests in both the epidermis (junctional component) and the dermis.
Question 4: Which stain is most useful for highlighting mucin deposition in the dermis, as seen in lupus erythematosus?
- Colloidal iron (or Alcian blue) (Correct answer)
- Congo red
- Fite stain
- PAS with diastase
Correct answer: Colloidal iron (or Alcian blue)
Colloidal iron and Alcian blue stain acid mucopolysaccharides, highlighting dermal mucin.
Question 5: A dermal tumor shows a proliferation of spindle cells with a 'storiform' (cartwheel) pattern and entraps fat, extending into subcutis. Which is most likely?
- Dermatofibrosarcoma protuberans (Correct answer)
- Dermatofibroma
- Neurofibroma
- Leiomyoma
Correct answer: Dermatofibrosarcoma protuberans
A storiform spindle-cell proliferation infiltrating fat in a honeycomb pattern and CD34-positive is characteristic of DFSP.
Question 6: Civatte bodies (colloid bodies) representing apoptotic keratinocytes are most characteristically found in which disorder?
- Lichen planus (Correct answer)
- Pemphigus vulgaris
- Spongiotic dermatitis
- Molluscum contagiosum
Correct answer: Lichen planus
Civatte (colloid) bodies are apoptotic keratinocytes seen at the interface in lichen planus and other lichenoid dermatitides.
Question 7: Immunofluorescence showing a linear IgG and C3 deposition along the basement membrane zone is characteristic of which blistering disease?
- Bullous pemphigoid (Correct answer)
- Pemphigus vulgaris
- Dermatitis herpetiformis
- Lichen planus
Correct answer: Bullous pemphigoid
Bullous pemphigoid shows linear IgG and C3 at the dermoepidermal basement membrane zone.
ABD Dermatopathology 2
A skin biopsy shows a 'sawtooth' pattern of the rete ridges with a band-like lymphocytic infiltrate at the dermoepidermal junction.
What is the diagnosis?