Page 64 - The Netter Collection of Medical Illustrations - Integumentary System_ Volume 4 ( PDFDrive )

Plate 2-37 Integumentary System

SPITZ NEVUS
Agminated
Spitz nevi
Spitz nevi are acquired nevi that occur most commonly
in children. The classic Spitz nevus is a benign growth
with minimal malignant potential. The Spitz nevus is
also known as a spindle-cell nevus. In the past, they
were also referred to as “benign juvenile melanoma,”
but that name should be avoided, because the term
melanoma should be used to describe malignant tumors Solitary Spitz nevus. Reddish-brown dermal papule
only. The difficulty with these melanocytic growths is
that they do not always have the classic appearance and
can be difficult to differentiate from melanoma. This is
especially true in the adult population, where Spitz nevi
are uncommon. For this reason, the terms atypical Spit-
zoid melanocytic lesion, atypical Spitz nevus, and Spitzoid
tumor of undetermined potential have made their way into
the dermatology lexicon to describe these difficult-to-
classify cases.
Clinical Findings: The classic Spitz nevus occurs in
childhood and has a characteristic reddish-brown color.
It has even coloration and regular borders. It is typically
dome shaped and smooth. It occurs equally in boys and
girls and is more commonly found in the Caucasian Low power. Symmetric melanocytic tumor, with
population. The most common location has been maturation of the melanocytes
reported to be the lower limb. The size is variable, but
they are usually 5 to 10 mm in diameter. Spitz nevi are
almost always solitary, but multiple Spitz nevi in an
agminated pattern have been described. The clinical
differential diagnosis of a Spitz nevus includes the
common acquired nevus, pilomatricoma, dermatofi-
broma, adnexal tumors, and juvenile xanthogranuloma.
Most Spitz nevi are asymptomatic and are brought to High power. Bland-appearing melan-
the clinician’s attention as an incidental finding. Classic ocytes predominate. A uniformity of
Spitz nevi rarely, if ever, spontaneously bleed or change cell size is seen, and no mitotic figures
in color. are appreciated. Melanophages are
Pathogenesis: The Spitz nevus is a melanocytic lesion present.
derived from spindle-shaped or epithelioid melano-
cytes. The initiating factor or factors that cause this
melanocytic proliferation to arise are unknown. They
are unique melanocytic lesions, and their pathogenesis
is likely to be entirely different from that of congenital
melanocytic or common acquired melanocytic nevi.
Histology: The classic Spitz nevus is symmetrically
shaped, without shouldering. It shows the proper
benign maturation of melanocytes from top to bottom
of the lesion. The melanocytes do not show pagetoid no immunohistochemical stain that can definitively dif- evaluation. Indeterminate lesions should be reexcised
spread (single melanocytes) within the epidermis. Spitz ferentiate a Spitz nevus from melanoma. As alluded to with conservative margins to make sure they have
nevi melanocytes in general have a spindle shape or earlier, the classic Spitz nevus is usually a straightfor- been completely removed. Spitz nevi in adults should
epithelioid morphology. Another helpful finding is the ward diagnosis. However, many difficult-to-classify all be excised to allow for complete histopathological
presence of eosinophilic Kamino bodies. These can be melanocytic lesions have overlapping features of Spitz examination. Unclassifiable or difficult to classify mela-
either solitary or coalescing into large globules. Kamino nevus and melanoma and can be exceedingly challeng- nocytic tumors with features of both Spitz nevus and
bodies are found in juxtaposition to the basement mem- ing diagnostically. melanoma are best treated as if they were melanoma.
brane zone and are composed of elements of the base- Treatment: Complete excision for a classic Spitz The Breslow depth should be used to plan for appropri-
ment membrane, specifically type IV collagen. There is nevus is curative and allows for a complete histological ate therapy.

50 THE NETTER COLLECTION OF MEDICAL ILLUSTRATIONS