Figure 5c. Retiform Sertoli-Leydig cell tumor of intermediate differentiation in a 32-year-old pregnant woman. (a) Axial T2-weighted MR image shows a large, lobulated, solid mass (arrowheads) with peripheral cysts (arrow). (b) Axial T1-weighted MR image shows that the contents of the cyst have slightly high signal intensity (arrow). Ut = uterus. Because the patient’s pregnancy was in the 12th gestational week, contrast material was not administered. The surgical specimen obtained at left salpingo-oophorectomy revealed a lobulated mass with rich solid components. (c) High-power photomicrograph (hematoxylin-eosin [H-E] stain) shows that thin cords of darkly staining Sertoli cells lie in the edematous stroma. The pathologic diagnosis was a Sertoli-Leydig cell tumor of intermediate differentiation with a retiform component. Although Sertoli-Leydig cell tumors are reported as predominantly solid masses, cyst formation is common in retiform subtypes and those with heterologous elements. The patient did not show any virilization; however, the serum level of inhibin A was elevated (190.2 pg/mL; normal level, <150 pg/mL), a finding that is another marker of a sex steroid-producing tumor.