(7) The accurate classification of a lesion as AST is challenging and often requires assimilation of the clinical presentation, histology, and ancillary studies to differentiate AST from ordinary Spitz nevus
If a physician is biopsying a possible Spitz nevus
, be sure the biopsy includes the lateral edges and enough of the dermis that the pathologist can make a good assessment.
Cytopathology of a Spitz nevus
in a child may show an alarming display of nuclear atypia, especially at the dermal-epidermal junction, but "vertically oriented aggregations of melanocytes get smaller as they go deeper."
Differentiation of Spitz nevus
from spitzoid melanoma can be problematic, as exemplified by the number of cases sent for consultation.
In most cases, the histologic differential diagnosis was between Spitz nevus
and spitzoid melanoma or between atypical nevus (such as variants of deep penetrating/clonal/inverted type-A nevus, pigmented spindle cell nevus, atypical genital nevus, atypical conjunctival nevus showing cytologic atypia, mitotic activity, limited maturation, or proliferative nodules, among others) and nevoid melanoma (Table 1).
Spindlecell and epithelioid cell nevi with atypia and metastasis (malignant Spitz nevus
Subsequent studies showed that the large bulky Spitz nevi, with sclerotic changes at the base, were morphologically the most likely type of Spitz nevus
to carry this isolated gain in 11p.
CAN ARRAY COMPARATIVE GENOMIC HYBRIDIZATION DIFFERENTIATE MELANOMA FROM SPITZ NEVUS
Melanoma.--The most challenging diagnosis is the subtype spitzoid melanoma (SM), which clinically and histopathologically resembles Spitz nevus
. (44) Lack of uniform opinion on which features enable this discrimination and absence of studies for validation of presumptive criteria (63) lead to misdiagnosis for up to 40% of children eventually found to have the disease.
(28) It is usually associated with a common compound or dermal nevus, or, much less frequently, Spitz nevus
. (23,29) Sclerosing (Desmoplastic) Blue Nevus Sclerosing BN, also known as a desmoplastic blue nevus, is an important morphologic variant of BN, which must not be confused with desmoplastic melanoma or a soft tissue tumor.
They include superficial and deep melanocytic proliferations with features reminiscent of Spitz nevus
(5) Most studies indicate that there are no BRAF mutations in Spitz nevus
(27-34); however, 1 study (35) reported that 21% (10/48) of Spitz nevi harbor a BRAF mutation, as compared to 15% (2/13) of spitzoid melanoma from the same study.