Interface and Lichenoid Dermatitis Flashcards
Interface and lichenoid dermatitis classification and ddx always includes ___
Other entities in the differential
Vacuolar vs lichenoid or associated epidermal changes
Drug reactions
Other differential:
- lichen planus
- Erythema multiforme and toxic epidermal necrolysis
- acute GVHD
- Lupus erythematosus
- Dermatomyositis
- Lichen nitidus
- Lichen sclerosus et atrophicus
- Perniosis (chilblains)
- Pityriasis lichenoides et varioliformis acuta (PLEVA) and pityriasis lichenoides chronica (PLC)
Lichen planus
Histology
DDX
Histology
- Band-like infiltrate
- Acanthosis with overlying orthokeratosis
- Jagged rete ridges
- Hypergranulosis
- Civatte and colloid bodies (dyskeratotic cells)
DDX:
- Lichenoid (fixed) drug reaction (eos and PK
- Lupus
- EM
- Lichen striatus
- Lichen planus actinicus
EM and TEN
Mild interface inflammation with necrotic keratinocytes prominent or confluent
TEN: full thickness epidermal necrosis (>30% surface area)
Stevens Johnsons has mucosal involvement
Acute GVHD
EM-like with
- vaculoar change
- Dyskeratotic cells
- periadnexal infiltrates
- no/few eos
Lupus erythematosis
Types with histology
Discoid LE:
- Epidermal atrophy
- interface
- Superficial and deep perivascular and periadnexal infiltrate of lymphs with PCs
- Dermal mucin (alcian blue or colloidal Fe +)
Subacute cutaneous LE and systemic SLE:
- similar to DLE but less infiltrate
- more vacuolar change
- apoptotic cells more prominent in SCLE
Lupus DIF
Positive “lupus band test”
IgG, IgM, IgA, +/- C3 along basement membrane
Dermatomyositis
Histology similar to LE but with milder epidermal atrophy and less inflammation
No deep or periadnexal infiltrates
Less mucin
Lichen nitidus
Small papillary dermal collections of lymphocytes (“ball in claw”)
Granulomatous appearance (not true granulomas)
Lichen sclerosis et atrophicus
Histology
DDX
Histology
- Atrophy
- Papillary dermal edema
- Collagen sclerosis
- Follicular plugging
DDX:
- Radiation dermatitis (perivascular hyalinization and radiation fibroblasts)
Perniosis (chilblains)
Acral site
Papillary dermal edema
tight perivascular lymphocytic infiltrates
lymphocytic infiltrates +/- lymphocytic vasculitis
Pityriasis lichenoides et varioliformis acuta (PLEVA) and pityriasis lichenoides chronica (PLC)
Histology
DDX
PLEVA:
- Crusting
- confluent PK
- dense wedge-shaped infiltrate
- RBC extravasation
- Exocytosis
- Scattered dyskeratotic cells
PLC
- Milder infiltrate with interface changes
- Few dyskeratotic cells
- Increased pigment incontinence
DDX:
- Contact derm
- lupus
- em
- drug reaction
- LyP
Interface Differential Chart from Elston
