A 36-year-old male with a history of immature teratoma and embryonal carcinoma of the testis was admitted to the hospital for abdominal pain and fever. A C T scan revealed a large right abdominal mass. The patient's serum alpha-fetoprotein (AFP) was 46.8 ng/ml (reference < 25 ng/ml). Fine-needle aspiration (FNA) of the mass revealed malignant glandular cells. Chemotherapy was instituted, followed by resection of the large abdominal mass. The tumor was grossly encapsulated, consisting of large areas of necrotic, hemorrhagic tissue surrounded by smaller, multiloculated cysts. Microscopically, the tumor had a villoglandular pattern and variably stratij?ed tall columnar cells. A prominent feature of the columnar cells was supranuclear and subnuclear vacuolization. Intracytoplasmic PAS-positive, diastase-resistant hyaline globules were occasionally present. AFP by immunoperoxid,ase was prominent within the tumor. This recurrence of the previously diagnosed testicular teratoma with embryonal carcinoma represents a yolk sac tumor with components strongly re.Pembling endometrioid carcinoma, a variant only recently de-sc>ribed in eight cases of ovarian origin (Clement et al.: A m JSurg P~rthol1987;11(10):767-778). We believe this is thejirst reported case of an endometrioid-like variant of testicular yolk sac tumor and also the first report of the FNA cytology jindings in this variant. Diagn Cytopathol 1992;8:600-604.