An Unusual Transformation of a Nonseminomatous Germ Cell Tumor to Adenocarcinoma

Abstract

Transformation of germ cell tumor to an alternate malignancy is rare; and it is believed to be secondary to teratomatous elements of the initial tumor surviving chemotherapy and subsequently proliferating. Here, we describe a patient with transformation of a nonseminomatous germ cell tumor to adenocarcinoma. A 55-year-old male with history of nonseminomatous germ cell tumor of the left testicle, previously resected, followed by four cycles of BEP chemotherapy, on active surveillance, presented nearly 20 years later with nausea and rising alpha-fetoprotein levels. Computed tomography (CT) abdomen revealed bulky retrocrural lymphadenopathy with increased fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET) scan. Biopsy revealed metastatic adenocarcinoma, staining strongly positive for SALL4 and CDX2, with focal rare positivity for CK20 in the tumor cells, consistent with germ cell origin. FOL-FOX therapy was therefore initiated. This is one of few documented cases showing transformation of nonseminomatous germ cell tumor to adenocarcinoma, for which surgical resection is favored as primary therapy. However, aggressive adjuvant chemotherapy may be considered and should be directed towards the most aggressive found histology.