Interphase fluorescence in situ hybridization analysis of chromosome 12p abnormalities is useful for distinguishing epidermoid cysts of the testis from pure mature teratoma.
OBJECTIVE
The distinction of epidermoid cyst of the testis from teratoma is of critical importance because the former is benign and the latter is a malignant tumor that may have associated metastasis of either teratomatous or non-teratomatous germ cell tumor types. Chromosome 12p abnormalities are seen in the vast majority of testicular germ cell tumors of adults and are present in all histologic subtypes. In this study, we investigated the clinical utility of interphase fluorescence in situ hybridization (FISH) analysis of chromosome 12p abnormalities for distinguishing epidermoid cysts of the testis from pure mature teratoma.


METHODS
Sixteen testicular epidermoid cysts and 17 testicular teratomas were investigated for isochromosome 12p [i(12p)] and 12p overrepresentation using interphase FISH analysis.


RESULTS
Neither i(12p) nor 12p overrepresentation were observed in 16 epidermoid cyst cases, whereas i(12p) was detected in 76% of teratomas and 12p overrepresentation was identified in 29% of teratomas. Overall, 88% of testicular teratomas had chromosome 12p abnormalities.


CONCLUSIONS
FISH identification of i(12p) and/or 12p overrepresentation in routinely processed surgical specimens is a useful ancillary diagnostic tool in distinguishing testicular epidermoid cysts from teratoma.
Cheng
Liang
L
Departments of Pathology and Laboratory Medicine, Indiana University School of Medicine, 350 West 11th Street, Indianapolis, IN 46202, USA. lcheng@iupui.edu
Zhang
Shaobo
S
MacLennan
Gregory T
GT
Poulos
Christopher K
CK
Sung
Ming-Tse
MT
Beck
Stephen D
SD
Foster
Richard S
RS
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D002869:Chromosome Aberrations; D002881:Chromosomes, Human, Pair 12 / Q000235:genetics*; D004814:Epidermal Cyst / Q000235:genetics*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D007399:Interphase; D007621:Karyotyping; D008297:Male; D013724:Teratoma / Q000235:genetics*; D013736:Testicular Neoplasms / Q000235:genetics*; D014407:Tumor Cells, Cultured