An isolated vaginal metastasis from rectal cancer: a case report.

INTRODUCTION: Vaginal metastasis from colorectal cancer is a rare occurrence, typically associated with other metastatic lesions. Isolated metastasis is exceedingly uncommon, with only a few cases documented in the literature. Vaginal involvement in colorectal cancer primarily results from direct contiguous spread from the primary tumor.

CASE PRESENTATION: We present the case of a 70-year-old African woman diagnosed with adenocarcinoma of the middle rectum. She underwent chemotherapy, radiotherapy, and subsequent anterior resection. After 2 months, an isolated metastasis of rectal cancer was identified in the lower third of the left vaginal wall, confirmed by biopsy. Colonoscopy ruled out colorectal recurrence. Thoraco-abdominal computed tomography scan showed no distant metastases. The patient underwent abdominoperineal resection, removing the lateral and posterior vaginal wall with free macroscopic margins and a definitive colostomy. The final histopathological analysis confirmed the diagnosis of moderately differentiated adenocarcinoma of the vagina, measuring 5 × 4.5 cm. The rectal wall was extrinsically invaded by the tumor down to the muscularis propria while respecting the rectal mucosa. Resection margins were negative. The patient was discharged 1 week postoperation with no complications. Adjuvant chemotherapy was indicated, and the patient is currently tolerating the treatment well.

CONCLUSION: Vaginal metastases from colorectal cancer are extremely rare. A vigilant gynecological examination is recommended during the follow-up of colorectal cancer patients. Diagnosis can be challenging, especially if the metastatic lesion is small and asymptomatic, even after standard radiological examination. Surgical resection followed by chemotherapy is a valid option for patients with early isolated metastases.