Signet ring cell carcinoma arising from sacrococcygeal teratoma: a case report and review of the literature.

We report here a rare case of adult sacrococcygeal teratoma (SCT) that was pathologically diagnosed as signet ring cell carcinoma (SRCC). A 26-year-old man complained of lower abdominal distension and discomfort and difficulty in urinating, and he was admitted to our hospital. Pelvic magnetic resonance imaging showed multiple oval, solid-cystic masses around the anterior sacrococcygeal region that measured approximately 96 × 114 × 89 mm. Magnetic resonance imaging also showed irregular cysts around the posterior sacrococcygeal region that measured approximately 34 × 72 × 60 mm. The preliminary diagnosis was cystic SCT. The patient then underwent surgery, during which we incised the cysts. A large amount of viscous, jelly-like liquid was present in the anterior sacrococcygeal mass. Furthermore, a large amount of light yellow, porridge-like secretion was present in the posterior sacrococcygeal mass. A pathological examination and immunohistochemistry confirmed teratoma, specifically SRCC.