Pure Testicular Seminoma Relapsing Late withSomatic Type Malignancy

Somatic type malignancy (STM) occurs in 2% of all germ cell tumours (GCTs). The prognosis is unfavourable andthe origin is poorly understood. Pathogenetic hypotheses involve direct transformation of teratoma, origin from totipotent cancercells, or derivation from yolk sac tumour elements.Case Presentation.A 31-year-old patient was cured from testicular seminomaclinical stage IIc by orchiectomy and cisplatin-based chemotherapy. Nine years later, he experienced a late relapse with a masssized5×6cm located at the former metastatic site. As no remission occurred after chemotherapy with three cycles of cisplatin,ifosfamide and etoposide, the mass was surgically resected. Histologically, the specimen consisted of neurofibroma with areas ofmalignant peripheral nerve sheath tumour and spots with mature bone formation. FISH analysis disclosed isochromosome 12p inthe majority of evaluated cells suggesting somatic type malignancy (STM) of GCT. The patient is well 1 year after surgery.Conclusion.The pathogenesis of this STM remains enigmatic. The origin from GCT was evidenced by documentation of isochromosome12p. Unrecognized teratomatous elements in the primary and totipotent cancer cells surviving the first chemotherapy could behypothesized to represent the origin. STM developing from seminoma cells would be another novel hypothesis