Letter to the Editor

Editor:

Are all testicular seminomas of animals in fact spermatocytic seminomas? Towards a comprehensive investigation.

Animal models, either spontaneously occurring or induced have been proven to be highly informative for cancer research in general. We demonstrated in 1994 that the canine testicular seminomas are most likely not a proper model for testicular seminomas of adolescent and young (mainly) Caucasian males, but of spermatocytic seminomas of elderly men ¹ . Based on recent data, tools have become available to explore this hypothesis in more detail. These include investigation of diagnostic markers ² ; detection of the protein OCT3/4-POU5F1 is a proper diagnostic marker for seminomas ³ , while SSX and DMRT1 are specific for spermatocytic seminomas ⁴ . Besides marker expression, the chromosomal constitution of the tumor cells is also informative to distinguish seminomas from spermatocytic seminomas ^{4– 6} . Human seminomas show characteristically overrepresentation of the short of chromosome 12, while chromosome 9 is specifically gained in spermatocytic seminomas ⁴ .

Our working model is that all tumors classified as seminomas in animals are in fact spermatocytic seminomas. To test this hypothesis, we would like to develop a tissue archive, to be organized in a so-called tissue micro array ⁷ of seminomatous tumors diagnosed in animals. These will be investigated for marker expression by immunohistochemistry and genomic studies using in situ hybridization techniques. This will shed light on the pathogenesis of human germ cell tumors, and elucidate the value of spontaneous animal tumors in this context.

We therefore ask the Veterinary Pathology Community to assist development of a unique tissue archive of seminomatous tumors of all species. For that purpose we would like to receive representative paraffin-embedded tissue.

Leendert H.J. Looijenga, J. Wolter Oosterhuis

Department of Pathology

Erasmus MC-University Medical Center Rotterdam

Daniel den Hoed Cancer Center

Josephine Nefkens Institute

Dr. Molewaterplein 50

3015 GE Rotterdam, The Netherlands

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