Biological significance of congenital melanocytic

Question 1

CMN are classified into 2 broad groups. Name the groups.

Answer 1

1. CMN blue type
2. CMN non-blue type

Question 2

CMN are classified into 2 broad groups. Which group is most common?

Answer 2

CMN blue type

Question 3

Name 3 types of Nevi belonging to “CMN blue type” group:

Answer 3

1. Mongolian spot
2. Nevus of Ota
3. Nevus of Ito

Question 4

CMN of the “non-blue” family are also defined as _________ ____ .

Answer 4

Superficial CMN

Question 5

Superficial CMN are divided into 3 groups by size. Name them.

Answer 5

1. Small CMN (<2 cm)
2. Medium CMN (2-20 cm),
3. Large CMN (>20 cm)

Question 6

Are Medium and large CMNs tumors or hamartomas?

Answer 6

Hamartomas.

Hamartomas are typified by a benign proliferation of melanocytes and keratinocytes

Question 7

Which groups of CMN are always present at birth

Answer 7

Medium and large

Question 8

Small CMN that present after birth are also known as _____ _________ _____ .

Answer 8

Early acquired nevi

Question 9

Why are small CMN thought to belong to the family of CMN even when they present after birth?

Answer 9

Because of similarity in terms of
1. morphological features
2. behavior

Question 10

Name Morphological features of Small CMN. Clinical and dermascopic.

Answer 10

Clinically: flat or slightly raised pigmented lesions

Dermoscopy: globular pattern

(Brown globules at the periphery is the hallmark of growing phase)

Question 11

How do small CMNs evolve? Clinical and dermascopic.

Answer 11

Clinical: become more elevated and acquire a papillomatous or smooth surface.

Dermascopically: brown globules at the periphery disappear, while a cobblestone pattern becomes visible throughout the lesion.

(After a variable time, usually years)

Question 12

What are the morphological features of medium and large CMN. Clinical and dermascopic.

Answer 12

Clinical: verrucous surface intermingled with terminal hairs. (Owing to keratinocytic proliferation)

Dermascopically: globular pattern, a reticular pattern or combination.

Question 13

What is neurocutaneous melanosis

Answer 13

Rare, potentially life-threatening condition where CMN involve the central nervous system

Question 14

When should you suspect neurocutaneous melanosis?

Answer 14

When large CMN is accompanied by multiple smaller CMN

(Satellitosis)

Question 15

What investigation is mandatory in neurocutaneous melanosis

Answer 15

Brain MRI within first year of life

Question 16

What is the usual lifecycle of small CMN?

Answer 16

1. Tend to persist over time
2. Undergo progressive maturation within the dermis

(May undergo spontaneous involution on nails and acral sites)

Question 17

Overall risk of melanoma in patients with CMN.

In 1 of the largest studies including more than 6500 patient’s with medium and large CMN the overall risk of developing melanoma was …

Answer 17

0.7%

(at a median age of 7 years)

Question 18

Risk of melanoma in patients with large CMN (> 40 cm).

In 1 of the largest studies are more than 6500 patient’s with medium and large CMN the risk of developing melanoma and CMN greater than 40 cm may reach ….?

Answer 18

10%

Question 19

Risk of developing melanoma in an acquired melanocytic nevus …?

Answer 19

Approximately 1 in 200,000

Question 20

Risk of developing melanoma risk in small CMN …. ?

Answer 20

Has not yet been calculated

Question 21

The majority of melanomas arising in pediatric population develop in what type of nevus?

Answer 21

Small CMN

Although the risk is small, the number of small CMN greatly outnumber medium and large CMN.

Question 22

What percentage of melanomas arising in pediatric population develop in CMN?

Answer 22

55%

Question 23

What percentage of melanomas in the adult population arise de novo?

Answer 23

70%

Question 24

Which is the most important melanoma precursor in terms of absolute numbers?

Answer 24

Small CMN

Question 25

What is the difference between a tumor and a hamartoma?

Answer 25

1. A tumor is a solid mass that forms when a group of abnormal cells clumps together.

(Tumors can be benign or malignant (cancerous)).

2. The defining feature of a hamartoma is that the cells that clump together are the same as the cells found in the surrounding normal tissue.

(The normal cells in a hamartoma grow together atypically.)