Dermatopathology Flashcards

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?

Answer: Lichen planus

Sawtooth rete ridges with a band-like (lichenoid) interface lymphocytic infiltrate are classic for lichen planus.

Munro microabscesses (collections of neutrophils in the stratum corneum) are a characteristic histologic feature of which condition?

Answer: Psoriasis

Munro microabscesses in the parakeratotic cornified layer are a hallmark of psoriasis.

A pigmented lesion demonstrates nests of melanocytes at both the dermoepidermal junction and within the dermis. This architecture defines which nevus type?

Answer: Compound nevus

A compound nevus has melanocytic nests in both the epidermis (junctional component) and the dermis.

Which stain is most useful for highlighting mucin deposition in the dermis, as seen in lupus erythematosus?

Answer: Colloidal iron (or Alcian blue)

Colloidal iron and Alcian blue stain acid mucopolysaccharides, highlighting dermal mucin.

A dermal tumor shows a proliferation of spindle cells with a 'storiform' (cartwheel) pattern and entraps fat, extending into subcutis. Which is most likely?

Answer: Dermatofibrosarcoma protuberans

A storiform spindle-cell proliferation infiltrating fat in a honeycomb pattern and CD34-positive is characteristic of DFSP.

Civatte bodies (colloid bodies) representing apoptotic keratinocytes are most characteristically found in which disorder?

Answer: Lichen planus

Civatte (colloid) bodies are apoptotic keratinocytes seen at the interface in lichen planus and other lichenoid dermatitides.

Immunofluorescence showing a linear IgG and C3 deposition along the basement membrane zone is characteristic of which blistering disease?

Answer: Bullous pemphigoid

Bullous pemphigoid shows linear IgG and C3 at the dermoepidermal basement membrane zone.