Spitz nevi display allelic deletions.
BACKGROUND
Spitz nevi are acquired benign melanocytic lesions that occur in childhood and adolescence. Histologically, they resemble malignant melanoma and were first termed benign juvenile melanoma. Several studies have attempted the difficult task of establishing diagnostic criteria to differentiate between Spitz nevi and malignant melanoma.


OBJECTIVE
To elucidate sets of diagnostic criteria for differentiation between the 2 lesions.


METHODS
We aimed to search for allelic deletions in Spitz nevi and to evaluate whether loss of heterozygosity (LOH) or microsatellite instability (MSI) would be a valuable diagnostic tool to differentiate between Spitz nevi and malignant melanoma.


METHODS
Two areas within each of 5 lesions were microdissected, and LOH and MSI were evaluated at chromosomes 6q (using polymorphic DNA marker D6S305), 9p21 (D9S171, IFNA, D9S265, and D9S270), 10q (D10S185), and 14q (D14S53).


METHODS
Five Swiss patients with Spitz nevi.


METHODS
None.


METHODS
Allelic deletions may serve as a diagnostic tool to distinguish Spitz nevi from melanoma.


RESULTS
All lesions were informative, displaying LOH or MSI with at least one marker. No LOHs were found at 14q. At 6q, MSI was found in 2 dissected areas from the same lesion; the remaining lesions were noninformative. Loss of heterozygosity was found in 2 of 6 areas at D9S171, 2 of 6 at IFNA, 3 of 6 at D9S270, 3 of 4 at D9S265, and 1 of 4 at D10S185. Microsatellite instability was found in 1 of 4 areas at D9S265.


CONCLUSIONS
With the markers used in our study, Spitz nevi display LOH and MSI similar to those in melanoma. Analysis of LOH or MSI is therefore not a suitable diagnostic tool in distinguishing Spitz nevi from melanoma.
Bogdan
I
I
Department of Dermatology, University Hospital Zurich, Gloriastr 31, 8091 Zurich, Switzerland.
Burg
G
G
Böni
R
R
D000293:Adolescent; D000328:Adult; D002648:Child; D002879:Chromosomes, Human, Pair 10 / Q000235:genetics; D002883:Chromosomes, Human, Pair 14 / Q000235:genetics; D002896:Chromosomes, Human, Pair 6 / Q000235:genetics; D002899:Chromosomes, Human, Pair 9 / Q000235:genetics; D003937:Diagnosis, Differential; D005260:Female; D018740:Genetic Heterogeneity; D005819:Genetic Markers; D006801:Humans; D019656:Loss of Heterozygosity; D008297:Male; D008545:Melanoma / Q000175:diagnosis* / Q000235:genetics; D018895:Microsatellite Repeats; D008875:Middle Aged; D018332:Nevus, Epithelioid and Spindle Cell / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology
D005819:Genetic Markers