Path

Question 1

Psoriasis

Answer 1

Epi:
- Confluent parakeratosis, hyperkeratosis
- Munro microabscesses: neutrophils in stratum corneum
- Spongiform pustules of Kogoj: neutrophils in spinous layer
- Regular acanthosis. Clubbed rete ridges
- Suprapapillary thinning
Derm:
- Dilated capillaries in dermal papillae
Perivascular lymphocytes

Question 2

Eczema

Answer 2

Epi:
-Focal parakeratosis
- Neutrophils in stratum corneum (if secondary infection)
- +/- acanthosis, hyperkeratosis (more if chronic)
- Spongiosis
Dermis:
- Superficial perivascular lymphocytes. Occ eos

Question 3

PLC

Answer 3

From 2021 examiner report
Parakeratosis
Mild lichenoid change
Occ apoptotic / necrotic basal keratinocytes
Top heavy or wedge shaped inflammatory infiltrate. Predominantly ymphocytes around BVs
RBC extravasation

Relevant negs:
No cd30+ve cells
No epidermotropism
No lymphocyte atypica
No Munro or Pautrier microabscesses

Question 4

PRP

Answer 4

Rapini and Bolog

Epi:
Follicular plugging
Shoulder parakeratosis adjacent to plugs
Psoriasiform dermatitis
Alternating vertical and horizontal ortho and parakeratosis, checkerboard pattern

Dermis:
Perivascular lymphocytes
Occ lichenoid

Vs psoriasis:
No neutrophils in PRP
No microabscesses of Munro (corneum) and spongiform pustules of Kogoj (spinous layer)
Hypergranulosis PRP vs hypogranulosis psoriasis
Psoriasis has dilated vessels in dermal papillae
Psoriasis has parakeratosis

Question 5

Granular parakeratosis

Answer 5

Path outlines

Epi:
- Thickened stratum corneum
- Parakeratosis
- Retention of basophilic keratohyalin granules in stratum corneum
- Mild spongiosis

Question 6

Lichen planus

Answer 6

Epi:
- Hyperkeratosis
- Irregular acanthosis with sawtooth pattern
- Wedge shaped hypergranulosis
- Apoptosis, vacuolar degeneration of basal layer
– Max Joseph spaces: vacuolar changes confluent, resulting in small separations in dermis-epidermis
- Civatte bodies (apoptotic/dyskeratotic keratinocytes in epidermis)

Dermis:
- Dense band like lymphocytic infiltrate in papillary dermis/dej
- Colloid bodies (apoptotic/dyskeratotic keratinocytes in dermis)

DIF:
- Shaggy band of fibrinogen

Question 7

Lichen nitidus

Answer 7

Well circumscribed infiltrate of lymphocytes, epithelioid cells, occasional Langerhans cells, confined to the width of 2-3 dermal papillae. ‘Clutched’ by surrounding hyperplastic rete ridges, ‘ball and claw’ configuration
Usually central parakeratotic ‘cap’
Absence or thinning granular layer
Vacuolar degeneration of basal layer
Lichenoid infiltrate closely apposes epidermis

Question 8

Urticaria

Answer 8

Rapini
Epi:
Normal

Dermis:
Oedema
Sparse perivascular and interstitial eosinophils, lymphocytes, neutrophils +/- mast cells

Question 9

LCV

Answer 9

Rapini
Epi:
- Normal to necrotic

Dermis:
- Fibrinoid necrosis of vessel walls
- Leukocytoclasia (breakdown of neutrophils), nuclear dust
- RBC extravasation
- +/- thrombi

DIF:
- Granular pattern in vessel walls. IgE, IgM, C3