Skin Pathology

Question 1

Microscopic appearance of Pityriasis rosea?

Answer 1

• Patchy epidermal spongioses (edema) & lymphocytes
• Patchy hyperkeratosis
• Parakeratosis
• Lymphocytes surrounding dermal vessels
• Extravasted red blood cells

Question 2

Microscopic appearance of Freckles?

Answer 2

Hyper pigmentation of the basal layer BUT no elongation of the rete ridges

• Cells of pigment are not melanocytes but rather epithelial cells
• In the dermis, a superficial chronic perivascular dermatitis with lymphocytes and rare plasma cells

Question 3

Microscopic appearance of Acanthosis nigricans?

Answer 3

• Epidermal acanthosis
• Hyperkeratosis
• Hyperpigmentation of basal layer

Question 4

Microscopic appearance of Melanocytic Nevi?

Answer 4

• Melanocytes in nests at the epidermal-dermal junction

- “Mongolian spots” Blue nevus

Question 5

Microscopic appearance of Dysplastic Nevi?

Answer 5

• Melanocytes in nests that fuse together

- Presence of cytological atypia

Question 6

Microscopic appearance of Eczema?

Answer 6

• Spongiosis leading to micro or macro vesicles.

- Accompanied by infiltration of lymphocytes into the epidermis and upper dermis.

Question 7

Microscopic appearance of Erythema multiforme? (DVD)

Answer 7

• Dead keratinocytes
• Vacuolar change
• Lymphocytes collecting along the dermal-epidermal junction

Question 8

Microscopic appearance of Lichen planus?

Answer 8

• Hyperkeratosis
• Thickened granular layer
• Band like infiltrate of lymphocytes (CD4+)
• Macrophages at Dermal-Epidermal junction
• Keratinocytes showing degeneration saw tooth pattern

Question 9

Microscopic appearance of Psoriasis? (PGR HAND)

Answer 9

• Hyperkeratosis
• Parakeratosis
• Acanthosis
• Reduced or absent stratum granulosum
• Regular elongation of rete ridges
• Neutrophilic aggregates (Munro’s microabscesses)
• Dilated tortured vessels

Question 10

Microscopic appearance of Pemphigus?

Answer 10

• Epidermis separates from from dermis
• an intra epidermal blister above the basal layer (suprabasal)
• Antibodies against desmosomes (loosening leads to acantholysis)

Question 11

Microscopic appearance of Bullous pemphigoid?

Answer 11

• Epidermis separates from dermis

- Ab against hemidesmosomes

Question 12

Microscopic appearance of Dermatitis herpetiformis?

Answer 12

• Neutrophils in the dermal papillae (papillary abscesses)
• Fibrin deposition
• Neutrophil fragments
• Edema

Question 13

Microscopic appearance of Epidermolysis Bullosa?

Answer 13

• Noninflammatory sub-epidermal blister

- Sparse perivascular lymphocytic infiltrate

Question 14

Microscopic appearance of Actinic Keratosis? (APE HO)

Answer 14

• Atypical keratinocytes occupy the lower portions of the epidermis
• Parakeratosis
• Orthokeratosis
• Hair Follicles with atypical epidermal keratinocytes “spare” hair follicle epithelium
• Elastosis in the dermis (aka: Fibrosis of dermis) –HALLMARK FEATURE

Question 15

Microscopic appearance of Bowen’s disease?

Answer 15

• Dysplasia

- Intact basement membrane

Question 16

Microscopic appearance of Seborrheic Keratosis?

Answer 16

• Sheets of small basaloid cells with some melanin production admixed with some squamoid cells
• Keratin production occurs at the surface
• Numerous horn (keratin pearls) are usually present

Question 17

Microscopic appearance of Leukoplakia?

Answer 17

• Hyperkeratosis, acanthosis
• Hyperplasia
• Sub epithelial inflammation
• Basal and parabasal cells are abnormal
• +/- Dysplasia which can lead to Carcinoma In Situ (involves the entire basement membrane)

Question 18

Microscopic appearance of Mycosis fungoides?

Answer 18

• Large, atypical lymphocytic infiltrate in the epidermis, which extends into the dermis-basilar epidermotropism
• Haloed lymphocytes
• Pautrier’s micro abscesses

Question 19

Microscopic appearance of Merkel cell carcinoma?

Answer 19

• Small cells with high nuclear/cytoplasmic ratio
• Hyper chromatic nuclei
• Blood vessel showing Azzopardi effects (basophilic debris of old DNA)

Question 20

Microscopic appearance of Squamous cell carcinoma?

Answer 20

• Sheets of atypical, malignant squamous cells (atypical keratinocytes), with keratin “pearls”
• Intercellular bridges

Question 21

Microscopic appearance of Basal Cell Carcinoma?

Answer 21

• Basophilic cells with hyperchromatic nuclei
• Nesting of malignant basal cells
• Clefting around cell nests
• Myxoid foci
• Peripheral palisading of the nuclei of the cells at the periphery of the tumor cell clusters

Question 22

Microscopic appearance of Malignant Melanoma

Answer 22

• Periphery condensed chromatin

- Prominent eosinophilic nucleoli

Question 23

Microscopic appearance of Urticaria?

Answer 23

• Superficial dermal edema

- Lymphatic dilation

Question 24

Microscopic appearance of Lichen simplex? (FPERCI)

Answer 24

• Elongation of the rete ridges
• Fibrosis of the papillary dermis
• Chronic inflammatory infiltrate

Question 25

Microscopic appearance of Seborrheic dermatitis?

Answer 25

• Malassezia furfur (spaghetti and meatball pattern)

- If hyphae are present than the diagnosis is Dermatomycosis

Question 26

Microscopic appearance of Molluscum contagiosum?

Answer 26

• Brightly eosinophilic dyskeratotic keratinocytes containing intracytoplasmic pox virus

Question 27

Microscopic appearance of Kaposi’s Sarcoma?

Answer 27

Atypical spindle cells lining slit like cascular spaces with extravasated red blood cells.

Question 28

Microscopic appearance of Warts?

Answer 28

• Hypertrophy of dermal papillae

- Thickening of the keratin layers of the epidermis

Question 29

Microscopic appearance of Impetigo?

Answer 29

Formation of blisters just under the stratum corneum (subcorneal blisters)

Question 30

Microscopic appearance of Vitiligo?

Answer 30

Absence of basal melanocytes

Question 31

Microscopic appearance of Rosacea?

Answer 31

You can see organism: Rosacea-Demodex folliculorum