The Journal of the Arkansas Medical Society Issue 2 Vol 115 | Page 20

Special Section: Short Dermatological Cases
Derm Dilemma
Rachel White, M3; Kevin St. Clair, MD
A
5-week-old baby of American
Indian descent presented at
birth with an extensive hyper-
pigmented patch involving the sa-
crum, buttocks, scrotum, and right
lower extremity. No other overt clinical
abnormalities were noted by the examin-
ing pediatrician. A skin biopsy demonstrated
banal appearing melanocytes involving the
deep dermal appendages and neurovascular
structures, as well as extension deep into the
subcutaneous adipose. Subsequent appropri-
ate step(s) in the evaluation or management
of this child should include:
A. Magnetic resonance imaging of the
central nervous system
B. Reassurance to the parents that no
further evaluation is necessary, as this
represents only a “Mongolian spot”
Answer: A
MRI of the CNS to exclude the presence of neurocutaneous melanosis approximately 5-7% risk of transformation to melanoma by age 60,
whereas risk of smaller lesions is not quantified but considered to be
much less. Posterior midline location, as in this patient, or association
with multiple satellite nevi are indications of potential underlying
neurocutaneous melanosis, which portends a poor prognosis. Staged
excision and laser therapy are eventual treatment options for CMN,
but MRI imaging to rule out neurocutaneous melanosis should be
obtained by age four months.
The described histologic findings indicate that this lesion is
a congenital melanocytic nevus (CMN), which is present in an
estimated 1-2% of newborns. These lesions are classified into
three groups: small (< 1.5 cm greatest diameter), medium (1.5-
19.9 cm), and giant (> 20 cm). Giant CMN are associated with an 1. Congenital dermal melanocytosis (Mongolian spot) generally
presents as localized blue-grey pigmentation of the sacrum, par-
ticularly in American Indians, Asians, and Hispanics. Spontaneous
resolution usually occurs in the first few years of life. In uncom-
mon situations where distinction from CMN is clinically difficult,
biopsy allows differentiation.
C. Urgent referral for Erbium-YAG laser therapy
D. Urgent referral to pediatric surgeon for staged excision
E. Genetic counseling for the parents
44 • THE JOURNAL OF THE ARKANSAS MEDICAL SOCIETY
VOLUME 115