Unusual Chemotherapeutic Resistant Testicular Embryonal Germ Cell Tumor with Widespread Metastasis in a Case of Klinefelter Syndrome: A Case Report

Cryptorchidism is an undeniable risk factor for testicular germ cell tumors (TGCTs) and is also commonly associated with Klinefelter syndrome (KS) patients. Embryonal cell carcinoma usually shows strong expression of CD30 and OCT3/4, with patchy staining of PLAP1. Most patients with nonseminomatous GCTs (NSGCTs) can achieve total remission with proactive chemotherapy, and most can be cured. We present an extremely rare case of a testicular embryonal germ cell tumor that is atypical in its gene expression and response to chemotherapy treatment. A 71-year-old male patient presented in July 2019 with abdominal pain of unknown duration, weight loss for one year, and recent history of altered bowel habits. His past medical history is significant for KS and congenital unilateral cryptorchidism. Physical examination yielded mild abdominal distention and bilateral inguinal lymphadenopathy. Imaging revealed a posterior mediastinal mass and large retroperitoneal masses. The above features, in addition to the history of KS and unilateral cryptorchidism, were highly suggestive of a testicular retroperitoneal germ cell tumor. Serologic studies revealed elevated lactate dehydrogenase (LDH) while other tumor markers were normal. Excisional biopsy of inguinal lymph nodes revealed poorly differentiated embryonal cell carcinoma with strong expression of SALL4, a rare expression of OCT 3/4, and the absence of expression of CD30 and placental alkaline phosphatase (PLAP). The patient was given four cycles of bleomycin, etoposide and platinum (BEP) chemotherapy, as is the standard chemotherapy regimen for these tumors, without any significant change in the size of the masses or lymph nodes. Unfortunately, there are no specific guidelines when it comes to the management of KS patients with testicular GCTs (embryonal cell carcinoma) with aberrant histological markers and normal serum tumor markers. These findings in combination with chemotherapeutic resistance indicate a need for more specific treatment modalities and follow-up for unusual testicular embryonal GCTs in KS patients.