1. Department of Obstetrics and Gynecology, Kansai Medical University, Hirakata, Osaka 573‑1191, Japan
2. Department of Pathology, Osaka Medical and Pharmaceutical University, Takatsuki, Osaka 569‑8686, Japan
3. Department of Pathology and Division of Diagnostic Pathology, Kansai Medical University, Hirakata, Osaka 573‑1191, Japan