Variants of melanocytic nevus Flashcards
What are 3 variants of melanocytic nevi?
Congenital melanocytic nevus
Halo nevus
Blue nevus
What percent of US babies are born with congenital melanocytic nevus?
1%
What is the appearance of the congenital melanocytic nevus lesion?
Similar to appearance of acquired form but larger in diameter
Brown-black plaque , usually a rough surface
Appearance changes over time
What is a common feature of congenital melanocytic nevus lesions?
Hypertrichosis (excess hair)
What is a very large congenital nevi called?
Bathing trunk or garment nevus
What is the histopathologic feature of congenital melanocytic nevus?
Similar to acquired form
What is the Tx for congenital melanocytic nevus?
Excision for esthetic purposes
Can congenital melanocytic nevus undergo malignant transformation?
Yes, 3-15% of large congenital nevi may undergo malignant transformation into melanoma
What is halo nevus?
Melanocytic nevus with a pale hypopigmented (or halo) border
Halo nevus is the result of what event?
Result of nevus cell destruction by the immune system
Immune cells attack the melanocytes adjacent to the nevus
When do multiple halo nevi develop?
Multiple halo nevi develop in patietns who have had a recent melanoma excision
At what age does halo nevus usually develop?
Second decade of life
Where on the body do halo nevi often develop?
Skin of the trunk
What is the clinical appearance of a halo nevus?
Central pigmented papule or macule surrounded by a uniform 2-3mm zone of hypopigmentation
Sometimes it may be wider
Tx for halo nevus
Tx is not reqd
Usually regresses entirely
Conservative surgical removal is curative and recurrence is unlikely
What effect explains the blue color of blue nevus?
Tyndall effect (interaction of light with particles in a colloidal suspension)
Where are the melanin particles in relation to the surface in blue nevus?
Deep to the surface
What is the clinical appearance of a blue nevus lesion?
Well-circumscribed deep blue macular lesion on palatal mucosa
What is the histopathologic feature of blue nevus?
Abundant melanin seen within spindle-shaped melanocytes deep within the lamina propria and parallel to the surface epithelium
Heavily pigmented spindle shaped cells
Tx for blue nevus?
Clinically indicated surgical excision is tx of choice
Biopsy blue nevus?
Yes bc oral blue nevus can mimic early melanoma
