Background: There are few reported cases of adenocarcinoma of unknown primary site (ACUPS) presenting with Trousseau's syndrome, and no cases presenting as an isolated retroperitoneal pelvic mass.
Case: This is a case of a 36-year-old woman who presented with an isolated "pelvic" mass and Trousseau's syndrome. The patient underwent abdominal hysterectomy and bilateral salpingo oophorectomy with resection of the retroperitoneal lymph nodes. Surgical findings included normal-appearing uterus, fallopian tubes, and ovaries, with bilaterally enlarged pelvic lymph nodes. Pathology was positive for adenocarcinoma only in the pelvic lymph nodes. Uterine, ovarian, and fallopian tube final pathologies were negative for malignancy. Postoperative metastatic survey was negative, and the patient was diagnosed with ACUPS. The patient received adjuvant chemotherapy consisting of etoposide, carboplatin, and taxol. The patient died 18 months after diagnosis.
Conclusion: This case reminds us that ACUPS can present as Trousseau's syndrome and rarely as an isolated retroperitoneal pelvic mass.