YouTube video Flashcards
What do you see?
acute spongiotic process
- this can be many things (if on acral sites, would think of dyshidrotic eczema, if there were necrotic keratinocytes, would think irritant contact dermatitis, etc.)
- classic psoriasis
- if there are no neuts in the stratum corneum this would just be “psoriasiform” dermatitis. Neuts are always present in psoriasis.
- if you see lots of eos with a picture that looks like PR, think drug reaction (can look like PR)
- this is a lichenoid reaction pattern (the lymphocytes are hugging the DEJ, this is not the same as perivascular infiltrate which does not come as close to DEJ)
- when you see lichenoid pattern differential narrows to:
1. lichen planus
2. LPLK (if solitary lesion clinically)
3. lichenoid drug (will see eos, which are never present in classic LP)
- eos are present here, what is your dx?
- this is a subcorneal neutrophilic pustolosis reaction pattern
With this, you can narrow differential to:
- pustular psroriasis
- AGEP
- Iga pemphigus
- Sneddon wilkison
SWIPA (Sneddon wilkinson, Iga pemphigus, pustular psoriasis, AGEP)
- to differentiate between AGEP and pustular psoriasis, look for features of psoriasis like loss of granular layer below the neutrophilic PK, thinning of suprapapillary plates= psoriasis
- if eos are present and classic psoriasis findings are not, then its AGEP
Erythema multiforme
- Here we see vacuolar interface change with dyskeratosis
- differential narrows to:
- Erythema multiform (dyskeratotic cells in all layers of epi with superficial PV lymphocytic infiltrate)
- acute GVHD (vs EM, will have dyskeratosis involving the follicles)
- fixed drug eruption (look for pigment incontinence, Eos, and dermal fibrosis)
Fixed drug eruption:
- we will see vacuolar interface with dyskeratosis, eos, pigment incontinence, and dermal fibrosis (eos, pigment incontinence and dermal fibrosis help differentiate from EM)
Discoid lupus:
- Vacuolar interface (can also be lichenoid)
- follicular plugging
- superficial to deep PV and perifollicular Dense lymphocytic infiltrate
- will see thickened BMZ with PAS stain
- will see increased mucin w/ colloidal iron
Drug eruption:
- we see PV lymphocytic infiltrate with eos, differential narrows to:
- drug
- bug (arthropod bite) (look for eos going deep into dermis/subQ) and wedge shaped infiltrate
- urticarial phase of BP (look for eos lining the DEJ)
Perniosis:
- note the acral site (helps with diagnosis of perniosis)
- papillary dermal edema (characteristic of perniosis, PMLE, and sweets)
- exocytosis of lymphocytes into epi
- superficial and deep PV and perieccrine lymphocytic infiltrate
- if you did colloidal iron would not have increased mucin (this along with acral site differentiate perniosis from lupus)
Angiosarcoma stains positive for:
CD31, CD 34, Factor VIII, cytokeratin
PLEVA
- also NO eos present
LCV
cryoglobulinemia
- will see lots of RBC extrav, clogged vessels with homogenous pink material
