HPV-related metastatic retroperitoneal pelvic squamous cell carcinoma of unknown primary origin in a patient previously treated for endometrial cancer.

Introduction: Cancer of unknown primary (CUP) is metastatic disease with no identifiable site of origin. Retroperitoneal squamous cell carcinoma of unknown primary is extremely rare. There are limited reports regarding treatment recommendations and outcomes for women with this disease.

Presentation Of Case: Here we present the case of a woman with human papillomavirus (HPV)-related metastatic retroperitoneal pelvic squamous cell carcinoma of unknown primary previously treated for endometrial cancer as well as a review of the existing reports on this topic. Surgical removal of the tumor was performed, the treatment had effective immediate results.

Discussion: There are a few reports describing CUPs in the retroperitoneal space. Most retroperitoneal tumors are asymptomatic and may be found incidentally during a regular examination, as in the case presented here. A full pelvic exam including inspection of the vulva, colposcopy and anoscopy should be performed, particularly in HPV-associated CUPs. Pathologic testing including immunohistochemistry and special staining and molecular testing of the tumor may be needed.

Conclusion: It is important to find the primary origin of cancer to treat it successfully. If the primary tumor cannot be identified, immunohistochemistry and molecular testing of the tumor may help identify the nature of malignant disease and help guide appropriate treatment.