Retroperitoneal sarcomatoid yolk sac tumor in a chemotherapy-naïve patient with testicular teratoma

Abstract

Abstract Introduction/Objective Sarcomatoid yolk sac tumor (SYST) is a rare histologic subtype of yolk sac tumor. In patients with testicular germ cell tumor, it is most frequently seen at the metastatic sites in the post-chemotherapy setting. SYST is rarely reported in chemotherapy-naïve testicular cancer patients in the existing literature. Herein, we report a rare concurrent retroperitoneal SYST in a chemotherapy-naïve testicular teratoma patient. Methods/Case Report A 37-year-old male presented with a 3.4 cm right testicular mass and a radical orchiectomy was performed, which demonstrated a pT1 teratoma with a separate adjacent regression fibrous nodule. His staging computed tomography revealed a heterogeneously enhancing and lobulated retroperitoneal mass measuring 9.6 cm in the greatest dimension. One month later, the mass enlarged to 26.3 cm. Fine needle aspiration biopsy revealed malignant spindle cell neoplasm with myxoid features, which displayed immunoreactivities for AE1/AE3, SALL4 and glypican 3, while was negative for OCT3/4, myogenin, SMA, desmin, S100 and CD34. Based on these findings, it was most compatible with SYST. The subsequent resection specimen showed a mass with soft fleshy to rubbery and friable gelatinous cut surfaces, and thorough tissue sections revealed the same histologic and immunophenotypic features as the prior biopsy. Therefore, a final diagnosis of SYST was rendered. Four cycles of cisplatin, etoposide, and ifosfamide (VIP) were administered, and the patient tolerated it well at his 6-month follow-up. Results (if a Case Study enter NA) NA Conclusion Here we presented a rare concurrent retroperitoneal SYST in a chemotherapy-naïve male patient who initially presented with a testicular teratoma. Due to its rarity, SYST may cause a diagnostic dilemma, and our case could raise awareness of this uncommon event and potentially expand the tumor spectrum.