Page 49 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 2-22 Benign Growths

BLUE NEVI

MELANOCYTIC NEVI

There are numerous types of melanocytic nevi, includ-
ing the benign congenital melanocytic nevi, the blue Blue nevus
nevi, and the common acquired melanocytic nevi. Atyp-
ical and dysplastic nevi are discussed with melanoma in
the section on malignant growths. Evaluation of mela-
nocytic nevi is one of the dermatologist’s most common
and important tasks. Every patient who enters a derma-
tologist’s office should be offered the opportunity to
have a full-body skin examination, specifically evaluat-
ing melanocytic nevi for any signs of malignant trans-
formation and or de novo melanoma production. The
importance of evaluating melanocytic nevi is to screen
for melanoma. Melanoma is a life-threatening skin
cancer that, if discovered early, can be cured. Different
types of melanocytic nevi have varying rates of malig-
nant transformation, and it is critical for the clinician
to be aware of those nevi that are likely to be encoun-
tered on a daily basis.
Clinical Findings: Melanocytic nevi can be classified
both clinically and histopathologically. The common
acquired melanocytic nevus is a clinical diagnosis, and
if the lesion is biopsied, it may show some evidence of
atypia or dysplasia of melanocytes. It is for this reason
that a universally accepted classification of melanocytic
nevi has yet to be adopted.
Benign melanocytic nevi are extremely common.
Virtually all humans have some form of these growths
on their body. Common acquired melanocytic nevi are
universally found and can have varying morphologies.
They affect males and females equally. They are uncom-
mon at birth but increase in number over the first 4
decades of life, after which the number typically stabi-
lizes. As one ages, the nevi tend to slowly involute.
They can be macular or papular in appearance. Most
are uniform and symmetric in size and color. They can
be flesh colored or slightly brown in coloration. They
tend to grow proportionally as a child grows or as an
adult gains weight. They also can become slightly larger
and darker during pregnancy.
There is a risk for malignant degeneration into mela-
noma, and changes in color, size, symmetry, or border
should be assessed. Nevi that become symptomatic,
especially pruritic, and nevi that spontaneously bleed
should be evaluated and biopsied appropriately.
Blue nevi are unique benign melanocytic tumors that
have a characteristic clinical and histological pattern.
These nevi tend to be small, to be located on the dorsal
aspect of the hands or feet, and to have a bluish to blue-
gray coloration due to their location within the dermis.
The blue color is believed to result from the Tyndall Blue nevus low power. The epidermis appears Blue nevus high power. Elongated pigmented
effect. This is a process by which various wavelengths normal. The dermis is filled with spindle-shaped melanocytes are appreciated with multiple dermal
of light are absorbed preferentially, and the reflected melanocytes and many melanophages. melanophages. The melanocytes are interspersed
light or color that is seen depends on the material and between the collagen bundles.
depth of the substance being illuminated. Blue nevi
share similar histological characteristics with the nevus
of Ota, nevus of Ito, and Mongolian spots. However,
the clinical appearance is so different that these lesions
are not considered in the differential diagnosis of a
blue nevus. occur anywhere, including the mucous membranes. is the case, but most of these lesions are actually
Blue nevi can occur at any age, and they appear They are frequently biopsied because of their unusual blue nevi. Malignant transformation of blue nevi is
equally often in men and in women. They typically coloration. They are small and usually can be removed extremely rare.
manifest as small (2-5 mm), oval or round macules or easily with a punch biopsy that is 1 mm larger than the Multiple blue nevi can be seen in the Carney complex,
papules. They are well circumscribed with nice, distinct lesion. Patients often give a history of having been also known as the NAME or LAMB syndrome. This
borders. They are commonly located on the dorsal stabbed with a pencil during childhood and believe complex of clinical findings includes multiple blue
aspect of the hands and feet but have been reported to that the lesion is a graphite tattoo. This occasionally nevi, lentigines, ephelides, myxomas, atrial myxomas,

THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS 35