Molecular evidence supporting the neoplastic nature of some epidermoid cysts of the testis.
BACKGROUND
Loss of heterozygosity (LOH) on chromosomes 9p and 12q is common in germ cell tumors of the testis. Loss of heterozygosity of 17p13 has also been demonstrated in germ cell tumors. The incidence of LOH in epidermoid cysts, a possible special form of teratoma, has not been previously determined.


OBJECTIVE
To determine the frequency of LOH in epidermoid cysts.


METHODS
Eight testicular epidermoid cysts and surrounding parenchyma were microdissected from formalin-fixed, paraffin-embedded tissue, and the genomic DNA was extracted using proteinase K. Polymerase chain reaction analysis targeted regions on chromosome 9p21 (D9S177 and D9S161 loci), chromosome 12q22 (D12S1051 locus), and chromosome 17p13 (TP53 locus). Gel electrophoresis followed by autoradiography was used to detect LOH.


RESULTS
All 8 of the epidermoid cysts were informative at a minimum of 1 of 4 loci. Three demonstrated LOH. In 2 tumors, LOH occurred on chromosome 9, and the third tumor demonstrated LOH on chromosome 12. Loss of heterozygosity on chromosome 17p13 was not present in any of the tumors.


CONCLUSIONS
Epidermoid cysts harbor allelic loss at some of the same loci identified in malignant testicular germ cell tumors. Our findings support that some examples of epidermoid cysts are neoplastic, although their low frequency of LOH also supports that they are genetically different from malignant germ cell tumors.
Younger
Cheryl
C
Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis 46202, USA.
Ulbright
Thomas M
TM
Zhang
Shaobo
S
Billings
Steven D
SD
Cummings
Oscar W
OW
Foster
Richard S
RS
Eble
John N
JN
Cheng
Liang
L
D002881:Chromosomes, Human, Pair 12 / Q000235:genetics; D002886:Chromosomes, Human, Pair 17 / Q000235:genetics; D002899:Chromosomes, Human, Pair 9 / Q000235:genetics; D004814:Epidermal Cyst / Q000453:epidemiology / Q000235:genetics*; D005557:Formaldehyde / Q000378:metabolism; D016158:Genes, p53 / Q000235:genetics; D005819:Genetic Markers / Q000235:genetics; D006801:Humans; D015994:Incidence; D019656:Loss of Heterozygosity / Q000235:genetics; D008297:Male; D016612:Paraffin Embedding; D013724:Teratoma / Q000235:genetics; D013733:Testicular Diseases / Q000235:genetics*; D013736:Testicular Neoplasms / Q000235:genetics*; D013737:Testis / Q000473:pathology*; D016707:Tissue Fixation
D005819:Genetic Markers; D005557:Formaldehyde