Therapy-resistant metastasizing anaplastic spermatocytic seminoma: a cytogenetic hybrid: a case report.

BACKGROUND: Anaplastic spermatocytic seminoma is a rare variant of the conventional spermatocytic seminoma, with only 6 cases reported up to now. The anaplastic variant contains only the medium-sized cell type, hallmarked by large-sized nucleoli, whereas the small lymphocyte-like and giant cells typical of the conventional spermatocytic seminoma are lacking. CASE: We report herein an unusual case of a 40-year-old man with an anaplastic spermatocytic seminoma which metastasized first to the retroperitoneal lymph nodes and, something never before reported, subsequently to the lung and other organs. The immunophenotype with c-kit and SALL4 positive and PLAP, as well OCT 3/4 negative tumor cells were identical to those of conventional spermatocytic seminoma. Cytogenetically the tumor cells showed a gain of chromosome 9, typical for spermatocytic seminoma, but simultaneously also the short arm 12p were overexpressed--an overexpression crucial to the aggressive behavior of seminomas and other nonseminomatous tumors but never before encountered in spermatocytic seminoma. CONCLUSION: The current opinion is that seminoma and nonseminomatous germ cell tumors develop from a common primitive progenitor cell, whereas spermatocytic seminomas develop from differentiated spermatogonia. The herein presented cytogenetic hybrid tumor shows that a crossover between the two different histogenetic "tracks" is possible.