The presence of human papillomavirus or p16 in six cases of retroperitoneal carcinoma

Objective: To describe six cases of unknown primary carcinoma of the retroperitoneum that were positive for human papillomavirus (HPV), a surrogate molecular marker for high-risk HPV (p16), or both. Methods: Using the MD Anderson pathology database, females with confirmed HPV or p16 expression within retroperitoneal carcinomas of unknown primary were identified. Clinical data were collected by retrospective chart review. One pathologist reviewed all histology. Individuals with known primary were excluded. Data regarding individual demographics, presentation, Pap test history, pathology, HPV and p16 positivity, and outcome were analyzed using descriptive statistics. Results: Six individuals were identified. The median age of the individuals was 43.5 years (range 27-54). Three malignancies (50%) were squamous and three (50%) were undifferentiated. Median follow-up was 12 months (range 6-48 months). Two of the six (33%) individuals had remote histories (more than 10 years) of abnormal Pap test results. All had normal gynecologic examination and Pap test results at diagnosis. Four tumors were HPV-positive (66%) and six were p16-positive (100%). All samples that were HPV-positive were also p16-positive. All individuals underwent treatment with chemotherapy, radiation, or both. One individual underwent initial attempt at resection that was unsuccessful. Two individuals are without evidence of disease, two have had progression of disease, and two have died of their disease. Conclusion: Pelvic masses of unknown primary may be HPV-related despite normal cervical examinations.