Skin 4 - Disorders of Pigmentation and Melanocytes

Question 1

What are the disorders of pigmentation and melanocytes?

Answer 1

1) vitiligo 2) albinism 3) Freckle (ephelis) 4) melasma 5) nevus (mole) 6) melanoma

Question 2

What are melanocytes responsible for?

Answer 2

skin pigmentation

Question 3

Where are melanocytes located?

Answer 3

They are present in the basal layer of the epidermis.

Question 4

What are melanocytes derived from?

Answer 4

the neural crest

Question 5

What do melanocytes do?

Answer 5

Synthesize melanin in melanosomes using tyrosine as a precursor molecule

Question 6

What do melanocytes do?

Answer 6

They pass melanosomes to keratinocytes

Question 7

What is vitiligo?

Answer 7

Localized loss of skin pigmentation

Question 8

What is vitiligo due to?

Answer 8

autoimmune destruction of melanocytes

Question 9

What happens in albinism?

Answer 9

It is a congenital lack of pigmentation

Question 10

What is albinism due to?

Answer 10

an enzyme defect (usually tyrosinase) that impairs melanin production

Question 11

What might albinism involve?

Answer 11

May involve the eyes (ocular form) or both the eyes and skin (oculocutaneous form)

Question 12

What is there an increased risk for in albinism and why?

Answer 12

Increased risk of squamous cell carcinoma, basal cell carcinoma, and melanoma due to reduced protection against UVB

Question 13

What is freckle?

Answer 13

(ephelis) small, tan to brown macule; darkens when exposed to sunlight

Question 14

What is freckle due to?

Answer 14

increased number of melanosomes (melanocytes are not increased)

Question 15

What is melasma?

Answer 15

mask-like hyperpigmentation of the cheeks

Question 16

What is melasma associated with?

Answer 16

pregnancy and oral contraceptives

Question 17

What is nevus?

Answer 17

(mole) benign neoplasm of melanocytes

Question 18

What is congenital nevus?

Answer 18

it is present at birth; often associated with hair

Question 19

When do you see acquired nevus?

Answer 19

it arises later in life.

Question 20

How does a nevus begin?

Answer 20

Begins as nests of melanocytes at the dermal-epidermal junction (junctional nevus);

Question 21

What is the most common mole in children?

Answer 21

nevus

Question 22

What is a compound nevus?

Answer 22

When the nevus grows by extension into the dermis

Question 23

What is an intradermal nevus?

Answer 23

The junctional component is eventually lost resulting in an intradermal nevus, which is the most common mole in adults.

Question 24

What is the most common mole in adults?

Answer 24

Intradermal nevus

Question 25

What is a nevus characterized by?

Answer 25

Characterized by a flat macule or raised papule with symmetry, sharp borders, evenly distributed color, and small diameter (< 6 mm)

Question 26

What might arise from a nevus?

Answer 26

Dysplasia may arise (dysplastic nevus), which is a precursor to melanoma

Question 27

What is melanoma?

Answer 27

Malignant neoplasm of melanocytes; most common cause of death from skin cancer

Question 28

What is the most common form of death from skin cancer?

Answer 28

Melanoma

Question 29

What are the risk factors for melanoma?

Answer 29

They are based on UVB-induced DNA damage and include prolonged exposure to sunlight, albinism, and xeroderma pigmentosum; an additional risk factor is dysplastic nevus syndrome,

Question 30

What is dysplastic nevus syndrome?

Answer 30

autosomal dominant disorder characterized by formation of dysplastic nevi that may progress to melanoma

Question 31

What does dysplastic nevus syndrome present as?

Answer 31

a mole-like growth with ABCD

Question 32

What is the ABCD for a mole like growth in dysplastic nevus syndrome?

Answer 32

1) Asymmetry 2) Borders are irregular. 3) Color is not uniform. 4) Diameter > 6 mm

Question 33

How is melanoma characterized?

Answer 33

by two growth phases

Question 34

What are the growth phases that characterize melanoma?

Answer 34

1) radial growth 2) vertical growth

Question 35

What is the radial growth in melanoma?

Answer 35

It grows horizontally along the epidermis and superficial dermis

Question 36

For radial growth, what is the risk for metastasis?

Answer 36

low risk of metastasis

Question 37

What is the vertical growth in melanoma?

Answer 37

It grows vertically into the deep dermis

Question 38

In vertical growth in melanoma what is the most important prognostic factor in predicting metastasis?

Answer 38

The depth of extension (Breslow thickness) is the most important prognostic factor in predicting metastasis.

Question 39

What are the variants for melanoma?

Answer 39

1) superficial spreading 2) lentigo maligna melanoma 3) nodular 4) acral lentiginous

Question 40

What is superficial spreading in melanoma?

Answer 40

most common subtype; dominant early radial growth results in good prognosis

Question 41

What is the prognosis for superficial spreading in melanoma?

Answer 41

Dominant early radial growth results in good prognosis

Question 42

What is lentigo maligna melanoma and what is the prognosis?

Answer 42

lentiginous proliferation (radial growth) good prognosis

Question 43

What is nodular regarding the variant of melanoma and what is the prognosis?

Answer 43

early vertical growth; poor prognosis

Question 44

What is involved in the Acral lentiginous variant of melanoma?

Answer 44

It arises on the palms or soles, often in dark-skinned individuals; not related to UV light exposure