ABSTRACT
A 56-year-old female was referred to our hospital due to a mass measuring 5 cm in size in the left pelvic cavity, which was found incidentally during a health examination by ultrasonography. Exploratory laparotomy was performed and the mass was located at the left retroperitoneal parametrium without invasion of the uterus and ovary. The pathology report confirmed squamous cell carcinoma. Even after further studies, we did not find any other primary lesion. Human papillomavirus (HPV) DNA chip test (HPV 9G DNA Membrane Kit, Biometrixtechnology Inc.) showed that the surgical specimen was positive for HPV 18. She received adjuvant chemotherapy and would receive radiation therapy for the possibility of occult gynecologic cancer. Retroperitoneal squamous cell carcinoma of unknown primary is extremely rare and little is known about it. It is reported that HPV may be associated with the disease. Hence, the result of HPV test could have an impact on finding a suspicious primary lesion and treatment modality in this case.