Congenital Melanocytic Nevus
 Defined as benign nevomelanocytic proliferations present at birth.
 Rarely, melanocytic nevi with features indistinguishable clinically and
histologically from typical congenital melanocytic nevi appear in children between
1 month and 2 years of age. This subset is termed nevus tardive
Classification
Small
Intermediate
Large
<1.5cm
1.5-19cm
>20cm
>2%BSA or 1%SA of Head
Clinical appearance
 Generally, congenital melanocytic nevi are round to oval in shape and have a
regular, smooth, and well-demarcated border.
 After the first 6 months, the lesions grow proportionally to the particular area of
the body involved
 Clinical appearance may change with age.
 In neonates, the moles may be light in color and relatively hairless, with a flat or
raised surface. As the child grows, the nevi may become progressively darker, with
a uniform brown to dark brown or black color and may acquire long, coarse, darkly
pigmented hairs.
 May exhibit a papular, rugose, pebbly, verrucous, or even cerebriform surfaces
 Satellite smaller melanocytic nevi may also be present,
 “Kissing nevus,” or divided nevus of the eyelid, is an interesting clinical variant of
congenital melanocytic nevi. It occurs on adjacent parts of the upper and lower
eyelids and appears contiguous, as a single lesion, when the eyelids are closed.
This finding implies that congenital melanocytic nevi develop between the 9th
and 20th week of gestation, when the eyelids are fused
Histology
1. nevomelanocytes splaying or extending between the collagen bundles of the
reticular dermis as single cells, “Indian” files, or cords of cells
2. nevus cells in lower 2/3rd dermis
3. extension of nevomelanocytes around and within hair follicles, sebaceous glands,
eccrine apparatus, vessel walls, and nerves
4. perivascular and perifollicular distribution of nevomelanocytes simulating an
inflammatory reaction such as figurate erythema
5. arrector pili that may be enlarged, distorted, and infiltrated by nevomelanocytes.
Atypical features of congenital nevi include
1. dysplasia of intraepidermal nevomelanocytes
2. pagetoid spread of nevomelanocytes - pagetoid intraepidermal growth
pattern in benign melanocytic nevi is confined to the area of nested
intraepidermal proliferation, in contrast to melanoma in which the pagetoid
growth is observed as lateral spread beyond the nested proliferation
3. proliferative dermal nodules.
Distinctive “Indian file” array of nevomelanocytes.
During the first 6 months of life, some nevi can appear to ‘‘grow’’ significantly as
tardive pigment becomes more visible.
Some satellite nevi may become visible for the first time over the first 2 to 3 years
(tardive CM)
Associations
 scoliosis, spina bifida, clubfoot, cranial bone hypertrophy
Neurocutaneous melanosis
 First described by Rokitansky
 presence of giant (2/3rd) or multiple(1/3rd) melanocytic nevi associated with benign
or malignant melanotic tumors of the central nervous system.
 posterior axial location, especially when associated with "satellite" melanocytic
nevi at greatest risk
 Called leptomeningeal melanocytosis with CMS melanoma
 Leptomeningeal melanoma present in upto 62% of the cases, but even in the
absence of melanoma, symptomatic neurocutaneous melanosis has an extremely
poor prognosis.
 Patients with large or multiple congenital melanocytic nevi in axial locations
(head, neck, or posterior midline) or multiple satellite lesions seem to have an
increased risk of leptomeningeal melanocytosis.
 Most case are sporadic, and no gender or racial predilection is evident.
 Melanocytes of both skin and leptomeninges are thought to be derived from
multiple potential precursor cells of the neural crest, NCM is postulated to
represent a congenital error in embryonic neuroectoderm morphogenesis.
 CSF shows increased protein, decreased sugar, and a normal cell count.. May show
melanin-filled cells
Criteria for the diagnosis of neurocutaneous melanosis:
(1) The presence of large or multiple congenital melanocytic nevi (one of which is at
least 20 cm in diameter) with benign (melanosis) or malignant (melanoma) central
nervous system (CNS) tumors.
(2) The absence of malignant melanoma in any organ (including skin) other than
the CNS.
Histology
 accumulation of melanotic cells in the arachnoid and pia mater
 Parenchymal melanin deposits probably represent melanocytes in the
perivascular spaces.
Clinical
Hydrocephalus – usually secondary to meningeal thickening,
Seizures
Mass lesions
Cranial nerve palsies
Mental retardation
Spinal cord compression
Investigations
MRI – T1 shortening characteristic
CSF cytology
Prognosis
 death occurred in more than half the patients within 3 years of the onset of
neurological symptoms, most <10 years old
Outcome
2 main concerns
1. Risk of melanoma
2. Stigma of visible lesion and how it will affect psychosocial development
Risk of melanoma
 In general, risk is related to nevomelanocytic load
 In several case series, no melanoma noted in small and intermediate lesions
 Approximately 50% of the malignancies that develop in large CMN do so in the
first 3 years of life, and 70% by puberty (<10yr old)
 Giant melanoma – 2 prospective studies
i. Ruiz-Maldonado (1992): Three of 80 patients (3.8%) developed cutaneous
melanoma during an average follow-up period of 4.7 years
ii. Marghoob (1996): Ninety-two patients were followed up prospectively for
an average of 5.4 years. Melanoma developed in 3 patients (3.3%) in
extracutaneous sites.
iii. Watt (PRS 2004) – review of 8 studies. Observed incidence of melanoma
was 2600 times higher than would be expected.
 majority of melanomas that arise in association with large or giant congenital
melanocytic nevi originate in the dermis. They are usually composed of epithelioid
cells, spindle cells, or small round cells.
 Melanomas arising in small congenital melanocytic nevi usually originate in the
epidermis
 To date, no case of melanoma has been reported arising in a satellite nevus
Treatment
Rationale for early treatment
1. greatest risk of melanoma during early years
2. elasticity and healing capacity of the skin in the early years
3. more tolerant to surgery /tissue expansion
4. psychological benefit
Treatment options
1. observation
2. dermabrasion
3. curettage
4. chemical peel
5. Q-switched ruby laser
6. staged excision and reconstruction
Dermabrasion and curettage
 remove the more concentrated population of nevus cells near the lesion’s surface.
 Theory is that the nevus cell migrate deeper with age
 can be effective in reducing the overall nevus ‘‘cell load’’ but cannot fully remove
the nevus, because of the well-known depth of nevus cells in CMN
 may result in significant lightening of the color of the lesion, it is quite common to
see later ‘‘bleed-through’’ of the deeper nevus, with gradual darkening and
reappearance of the lesion.
 lightening of pigmented giant congenital nevi using these techniques may make it
more difficult to monitor the resultant lesion for signs of malignant transformation,
because alteration in pigmentation of the lesion can no longer be followed reliably.
 no longitudinal studies documenting decreased rates of malignant transformation
after laser or dermabrasion treatment.
Reconstruction
 there is no evidence in the existing literature that the excision of large
congenital melanocytic nevi decreases the prevalence of melanoma.
Serial excision
 undertaken if lesion can be removed in 3-4 excisions. Otherwise tissue expand.
SSG
 SSG or full thickness grafts(preferred)
o FTSG donor sites – postauricular, supraclavicular, buttock, groin, medial
arm, abdomen
o May be expanded to increase donor area
o Use of Integra at recipient site may improve scar
Tissue expansion (Bruce Baeur)
 Advantage - large flaps of color-, thickness-, and texture-matched skin while
simultaneously minimizing donor-site defects.
 optimized to ensure that the landmarks of the forehead aesthetic unit will be
disturbed as little as possible.
 Particular emphasis is placed on brow symmetry, temporal hairline position and
hair direction, and scar orientation.
Scalp
 Treatment starts as early as 6 months, with some cranial molding expected by the
time the expanders are removed
 No instance of long-term cranial deformity has been noted (remodeling usually
occurs over 3 to 4 months).
 Rectangular expanders with remote ports, placed subgaleal (250-500ml size)
 Usually 2 expanders used
 Expanded weekly, 2nd stage in 10 weeks
Face
 Unilateral forehead – hemiforehead expansion
 Central forehead – bilateral forehead expansion
o Expanders placed subfrontalis
o Because many of these nevi involve the adjacent scalp, the combined
‘‘attack’’ on both of these regions often facilitates the excision and aesthetic
outcomes
 Cheek – postauricular and neck flaps
 Eyelids – best with FTSG, donor site may be preexpanded to increase donor area
and reduce seams.
 Brow can be reconstructed with island flaps from temporalis (below), or hair
bearing FTSG or with micrograft hair transplants
Torso
 Early expansion successful for lower or central abdomen, back and buttocks
 Expansion must be avoided in or around the area of the breast bud in females,
and lesions of the breast should be left until after breast development, regardless of
the psychological implications of delaying the treatment till that age.
 Bathing trunk nevus – reconstruct only areas in which reconstruction can
reasonably be expected to provide a better aesthetic and functional outcome than
the original lesion, even if this means leaving residual nevus in the genital and
perineal regions
Extremities
 Serial excision is the preferred treatment modality for lesions at or just proximal to
the knee or elbow.
 Similar lesions distal to the knee or elbow are difficult to treat using serial excision
alone because of reduced skin compliance and reduced diameter of the distal
extremity.
 Expanded skin grafts have been used but long-term follow-up of these patients
typically demonstrated contour deformities and unacceptable aesthetic outcomes.
There are also concerns about both the durability of these grafts and their ability
to keep up with normal extremity growth.
 Expanded full-thickness skin grafts have been used effectively for the dorsum of
the hand, with excellent aesthetic outcomes
 geometry of the extremity, as well as the limited flexibility of the skin (particularly
in the lower extremity) makes regional expansion of limited use.
 Skin grafts generally used below the knee
 In selected cases
o large expanded transposition flaps from the scapular region to cover the upper
arm and shoulder and expanded or nonexpanded pedicle flaps from the flank
and abdomen for circumferential nevi from the elbow to the wrist.
Summary
Early surgical intervention with multiple staged excisions with tissue expansion and
or grafting is the best approach as well as close clinical follow-up for the remaining
areas that are too difficult to be removed or in areas that would produce too much
scaring.