Sex cord tumor with annular tubules associated with endometriosis of the fallopian tube.

Sex cord tumor with annular tubules (SCTAT) is a distinctive ovarian sex cord-stromal tumor. The authors describe a case of SCTAT arising outside the ovaries, in the fallopian tube. The authors are aware of only one other case of extra-ovarian SCTAT, in an umbilical hernia sac in an adult woman. The case reported was an incidental finding in a hysterectomy specimen, obtained because of carcinoma in situ of the uterine cervix in a 32-year-old woman. The patient is alive and disease-free two years after surgery. The 1-cm tumor in the right fallopian tube was composed of typical ring-shaped tubules encircling hyalinized basement membrane-like material. In addition, glands and stroma of endometriosis were intimately admixed with the nests of tumor. The implications of these findings for the origin of SCTAT and ovarian sex cord structures are discussed.