Melanocytic neoplasms

Question 1

Ephelides (feckles)

Answer 1

Question 2

CALM (cafe-aulait macule)

Answer 2

1. Discrete uniform tan to brown macules /patches 2-5cm, may be seen in infants children, and young adults; isolated funding in 10-20% of normal population
2. Multiple CALM may be a/w numerous genodermatoses:
   -Neurofibromatosis type 1>2
   -Mcune-Albright syndrome
   -russel silver
   -noonan syndrome
   -bloom syndrome
   -tuberous sclerosis
   -MEN-1
   -Fanconi syndrome
   -Ataxia-telangiectasis
   Histology: increased melanin deposition in basilar keratinocytes

Question 3

Solar lentigo

Answer 3

Question 4

Lentigo simplex

Answer 4

1. Well demarcated evenly pigmented brown-black macule, any age/anatomic site (inlcuding mucous membranes), <5mm
2. If eruptive -> lentiginosis
3. Histology: basal layer hyperpigmentation, elongated rete ridges with mild increase in melanocyte density (most common histo seen in longitudinal melanocyhia)
4. Causes: irritation, PUVA, hormones, acral -> genetic (darkly pigmented)
5. If generalized - isolated OR a/w genetic d/o
6. does not favour sun exposure
7. Can develop in scars post surgery for melanoma
8. conditions a/s multiple lentigines
   - LEOPARD
   - Carney complex (LAMB/NAME)
   -Peutz-Jeghers (esp oral/peri-oral)
   - Laugier-Hunziker
   -Cowden syndtome
   -Bannayan-Riley-Ruvalcaba (penile)
   -Xeroderma pigmentosum
   -Cronkhite Canada

Question 5

Mucosal melanotic macule

Answer 5

1. Compared with lentigo simplex, genital and oral, can be more irregular/mottled
2. Some acral/mucosal lesions = atypical, if in doubt -> biopsy
3. Oral lesions usually occur in adults > 40y on vermillion border > gingiva, buccal mucosa, or palate, genital lesions most common on labia minora
4. Histology: acanthosis, mild basilar hyperpigmentation, +~ subtle increase in melanocytic density
5. 30% of melanoma of oral cavity in caucasians are preceded by melanosis of the oral cavity

Question 6

Dermal melanosis

Answer 6

1. Congenital (Mongolian spot)
   -present at birth in most Asians and blacks; lumbosacral region, presents with gray-blue patch (as a result of the Tyndall effect) where shorter wave-lengths are reflected by melanocytes
   -often resolves during childhood
   -histology: sparsely distributed, elongated dendritic melanocytes in lower 2/3 dermis, lying paralellel to epidermis
   -melanocytes migrate 10th week -> deposits in sacral area etc
   -if extensive comsider phakomatosis type 2
   -if CALM/lentigo in area -> white halo
2. Nevus of ota
   -present in 1st year of life/puberty
   -increased incidence in pigmented individuals (Asians/black pt)
   -p/w coalescing gray/blue macules in V1/V2 distibution and frequent scleral involvement (60%), unilateral (90%) > bilateral, persists for life, may enlarge under hormonal influences, 10% develop glaucoma; rare malignant degeneration to uveal melanoma and cutaneous melanoma (perhaps a higher risk in nevus of Ota lesions with activating mutations in GNAQ)
   -Histology: elongated, dendritic melanocytes more numerous than in congenital dermal melanocytosis, involves upper dermis
   -pathogenesis: hamartoma, mutation in GNAQ, hormonal, BAP1 mutation -> potential malignant melanoma transformation
   -can affect retina, optic nerve, nasal mucosa/pharynx
   -neuromelanomas/meningeal melanocytoma
   Other clinical variants
3. Nevus of Ito - located on the shoulder, supraclavicular, and scapular regions, essentially no risk if progression to melanoma
   - Blue-brown
   -can occur with nevus of ota or isolated
4. Hori’s nevus : acquired nevus of ota-like macules bilateral zygomatic region; East Asian females
5. Sun’s nevus: acquired, unilateral variant of Hori’s nevus
   Mnemonic : there is only 1 sun, but the (w)HOle face is affected in Hori’s
6. other variant = patch blue nevus -> grey-blue diffuse area + superimposed darker macules
   HISTO of dermal melanosis
   Dermal melanocytes are distinguished from blue nevi by their decreased cellularity, poor circumscription and lack of dermal sclerosis

Question 7

Blue nevus

Answer 7

Question 8

Recurrent melanocytic nevus

Answer 8

1. Repigmentation confined to the scar (vs pigment extending beyond biopsy site = melanoma)
2. Usually arises within 6 months of initial biopsy
3. common following shave
4. Histology: 3 key features
   - dermal scar
   -atypical junctional melanocytic proliferation (resemble MIS) confined to area above dermal scar
   -Bland dermal nevus remnants below/adjacent to scar

*If irregular, beyond scar, large interval from biopsy -> consider melanoma