Pelvic accessory spleen caused dysmenorrhea.

Accessory spleens (AS) are congenital malformations defined as additional ectopic splenic parenchyma. Most of them are innocent until found, and do not usually require treatment. They may have clinical significance since theymay be confused for enlarged lymph nodes or have a neoplastic appearance; therefore, accurate preoperative diagnosis is important to avoid unnecessary surgical management. Herein, we share a rare case of pelvic AS which caused secondary dysmenorrhea mimicking pelvic neoplasm. Gynecologists should be aware of the possible existence of AS in the pelvic cavity in order to make a precise preoperative diagnosis. A 38-year-old woman with secondary dysmenorrhea was referred for an incidentally detected pelvic mass in a local hospital.