L4

Question 1

Macule

Answer 1

Circumscribed flat lesion of up to 5 mm in diameter

Question 2

Patch

Answer 2

Circumscribed flat lesion >5 mm in diameter

Question 3

Papule

Answer 3

Elevated dome-shaped or flat-topped lesion 5 mm or less

Question 4

Plaque

Answer 4

Elevated flat-topped lesion usually greater than 5 mm

Question 5

Nodule

Answer 5

Elevated lesion with spherical contour greater than 5 mm

Question 6

Vesicle

Answer 6

Fluid-filled raised lesion 5 mm or less

Question 7

Bulla

Answer 7

Fluid-filled raised lesion greater than 5 mm

Question 8

Blister

Answer 8

Common term used for vesicle or bulla

Question 9

Pustule

Answer 9

Pus-filled, raised lesion

Question 10

Wheal

Answer 10

Itchy transient elevated lesion as a result of dermal edema

Question 11

Scale

Answer 11

Dry horny lesion because of hyperkeratosis

Question 12

Hyperkeratosis

Answer 12

Thickening of the stratum corneum

Question 13

Parakeratosis

Answer 13

Retention of the nuclei in the stratum corneum

Question 14

Acanthosis

Answer 14

Diffuse epidermal hyperplasia

Question 15

Papillomatosis

Answer 15

Surface elevation caused by hyperplasia of dermal papillae

Question 16

Dyskeratosis

Answer 16

Abnormal keratinization below the stratum granulosum

Question 17

Acantholysis

Answer 17

Loss of cohesion between keratinocytes

Question 18

Spongiosis

Answer 18

Intercellular edema of the epidermis

Question 19

Seborrheic keratosis

Answer 19

benign
 Single or multiple, sharply demarcated pigmented lesion
 Protrudes above surface of skin
 Soft, tan-black, “greasy” surface
 Few millimeters to several centimeters in size
 Can occur anywhere except palms and soles; commonly on trunk also the scalp

Leser-Trélat sign:
 Sudden appearance,↑ in number and size of seborrheic keratoses
 Associated with internal malignancy
 Paraneoplastic: associated with GI malignancy

Micro: proliferation of squamous epithelium + cysts filled with keratin

 FGFR3 activating mutations

Question 20

Actinic keratosis

Answer 20

premalignant
 Due to excessive, chronic exposure to sunlight -> TP53 mutation
 Considered as “premalignant” proliferation
 Hyperkeratotic, scaly plaques on the face, neck, limbs & trunk
 Affects most commonly old patients
 Basal cell and squamous layer atypia and disorderly maturation, hyperkeratosis, parakeratosis
 In situ -> Invasive Squamous Cell CA.

Question 21

Malignant tumors

Answer 21

Very common
Majority present on sun-exposed skin
A) Basal cell carcinoma
B) Squamous cell carcinoma

Question 22

Basal cell carcinoma حييل مشهور وشبه يومي

Answer 22

 Most common malignant tumor
 Due to sun exposure in patients over 40 with fair skin
 Mainly on face, Sun exposed skin, never mucosal
 Infiltrative but NO METASTASIS!
 Pathogenesis:
- Defects in DNA repair & TP53 mutations
- PTCH gene mutation – Hedgohog Pathway
 Gorlin Syndrome
 Rx: Surgical Excision
 40% of treated develop a new BCC in 5 years
 Superficial multifocal or Nodular growth
Other variants:
 Ulcer (Rodent Ulcer)
 Pigmented
 Basosquamous
Micro: nests of epithelial cells that resemble basal cells forming palisades separated from surrounding stromal fibroblasts by a cleft-like space

Question 23

Squamous cell carcinoma

Answer 23

 Common tumor but less common than BCC
 Develops in sun-exposed skin of fair patients with light hair & freckles, non-exposed skin or mucosa
 Etiology:
Exposure to sunlight, UVB light & radiation
Arsenicals & industrial carcinogens (tar, oil)
Actinic keratosis
Any chronic scarring processes, (burn, scars, chronic ulcers)
Immunosuppression (HPV 16 & 18)
Xeroderma pigmentosum
 Genes involved: TP53, Notch receptors, HRAS
 Sites: dorsal surface of hands, face ,ears, mucosal surfaces
 Small lesion initially -> ulceration later
 Microscopic
Full thickness epidermal dysplasia (CA in situ)
Invasive carcinoma
Variable degree of keratinization (differentiation)
 Increased tendency to infiltrate and metastasize locally to LN

Question 24

Melanocytic Tumors of the Skin

Answer 24

1. Melanocytic NEVUS (mole/common nevus)
2. Dysplastic Nevus
3. Malignant melanoma

Question 25

Melanocytic NEVUS (mole/common nevus)

Answer 25

 Commonest benign tumor in the body  Derived from dendritic melanocytes (basal layer of the epidermis)  Contains melanin pigment  Immature at junction, but mature as cells migrate down into dermis  BRAF or NRAS mutation identified  There are several types: junctional, compound and intradermal  Uniform small (<5 mm)  Microscopic picture: nests or cords of uniform nevus cells ± pigment  Malignant transformation is uncommon

Question 26

Dysplastic Nevus

Answer 26

 Sporadic: Low risk of malignant transformation  Familial: Autosomal dominant with melanoma risk up to 100%  Considered as a marker for development of melanoma  Usually multiple, on exposed or unexposed skin  Activating BRAF or NRAS mutations  Features: increased melanocytes, junctional cytologic & architectural atypia & dermal fibrosis around proliferating cells