A Blood Cyst in the Pelvic Cavity Must be Distinguished from a Submucosal Rectal Tumor—A Case Report—

Abstract

A 42-year-old Japanese man was referred to our hospital for lower abdominal pain. Colonoscopy suggested a sub-rectal mass, which was identified as cystic disease in the pelvic cavity on computed tomography and magnetic resonance imaging. He underwent surgery for the precise diagnosis of his persistent constipation. The mass, located between the bladder, seminal vesicle, inferior abdominal nerve pelvic plexus, and upper part of the rectum, was totally removed as a lump with the adjacent fat tissue. Immunohistopathological examination showed that the mass contained bloody fluid and inner lining cells that were positive for CD31 and CD34, diagnosing a true blood cyst. The patient remains well without postoperative recurrence. Blood cysts are commonly located in the neck ; therefore, it is difficult to diagnose them preoperatively when they occur in other sites. It may be important for physicians to bear in mind that a blood cyst can also present as a submucosal rectal tumor.