Immature renal tissue occurring in cystic teratoma of ovary.

A 25-year-old, G0P0 female had bilateral cystic teratoma history and had undergone laparoscopic partial oophorectomy at the ages of 18 and 22. A right ovarian mass was found on sonography during follow-up (Figure 1A). Subsequent contrast-enhanced computed tomography showed a 5.7 cm ovarian teratoma with ascites (Figure 1B). Two months later, she suffered from progressive abdominal cramping pain and visited the emergency room. Physical examination showed severe tenderness over the right lower abdomen. Lab data, including complete blood count, C-reactive protein, CEA, CA199 and SCC, were within the normal range. Under the suspicion of ovarian teratoma with torsion, laparoscopic partial oophorectomy was performed (Figure 1C). The specimen was totally embedded. Microscopically, the tumor contained solid and cystic components. The cystic part was lined by stratified squamous epithelium with pilosebaceous