Lichenoid reaciton pattern

Question 1

Label

Answer 1

Question 2

Dx and DDx

Answer 2

Lichen Planus

DDx:
- Lupus
- Lichenoid drug eruption
- Lichenoid keratosis
- DM

Question 3

What are the key feature of Lichen Planus?

Answer 3

Compact hyperkeratosis, usually without parakeratosis

Wedge shaped hypergranoluosis

Vacuolar change at the basal layer layer is apoptotic keratinocytes (civatte bodies)

Lymphocytic infiltrate along the DEJ

Colloid bodies in the papillary dermis (apoptopic keratinocytes)

Saw tooth appearance of the rete ridges

Pigment incontinence

Question 4

W

What do you expect to see on DIF for LP?

Answer 4

IgM, C3 and fibrin staining of the colloid bodies in the dermis.

Question 5

Describe, preferred Dx

Answer 5

Dense infiltrate in the papillary dermis, localised between two derm papillae - resulting in a ‘claw like appearance.

Overlying epidermal atrophy and parakeratosis

Preferred Dx = Lichen nitidus

Question 6

Label and Dx

Answer 6

Question 7

DDx of Lichen Nitidus?

Answer 7

LP
Arthropod bite reaction

Question 8

Label

Answer 8

Question 9

Label

Answer 9

Question 10

Describe

Answer 10

Band like blue cel infiltrate
Apoptoptic keratinocytes
pigment incontinence
hyperkeratosis and focal parakeratosis

Lack of wedge like hypergranulosis