Melanocytic Neoplasms

Question 1

Answer 1

Spitz nevus

Question 2

Answer 2

Neurotized nevus

Question 3

Answer 3

pigmented spindle cell nevus of reed

Type of Spitz nevus

heavily pigmented

Usually junctional

Young adults

Extremities

Question 4

Answer 4

Blue nevus

Histology:

• dendritic and spindled pigmented melanocytes
• melanophages
• Sclerotic stroma
• small and superficial
• lack mitoses and atypia

Cellular blue nevi are larger, have fascicular growth with nests of hypopogmented oval to spindled melanocytes, deep adn bulbous (“dumbbell shaped”), extend into fat and have few mits

Question 5

Characteristics of dysplastic nevus

Answer 5

1. bridging of rete
2. ascension of single and nested melanocytes along sides of rete
3. occasional lentiginous and/or pagetoid cells
4. variable cytologic atypia (mild to severe)
5. lamellar or concentric fibroplasia
6. variable dermal chronic inflammation with melanophages
7. mitoses absent/rare

Question 6

Pagetoid spread in melanoma in situ

Answer 6

Common in superficial spreading type and uncommon in lentigo maligna

Question 7

Nevus HMB-45 staining

Answer 7

Loses staining at base

Question 8

Histology

Immunos

DDX

Answer 8

Desmoplastic melanoma

Histology:

• dermal spindle cells with sclerosis
• look for overlying intraepidermal component
• neurotrophism
• lymphoid aggregates around tumor

Immunoperoxidase:

Positive: S-100

Negative: HMB-45, Mart-1/Melan A,

MEL-CAM and NK1/C3 may be positive

DDX:

1. spindle cell SCC (HMWCK +, p63+)
2. AFX (S-100 negative, CD10 +, CD68 +)
3. desmoplastic nevus (less atypia, more superficial, no mits or lymphs)