# A case of rectal metastasis of prostate cancer mimicking extramural growth-type rectal tumor

## TL;DR

A rare case of prostate cancer spreading to the rectum was mistaken for a different type of tumor, highlighting the need for careful diagnosis.

## Contribution

This case report highlights the diagnostic challenge of rectal metastasis from prostate cancer resembling an extramural rectal tumor.

## Key findings

- The patient had a rectal tumor that was later confirmed to be a metastasis from prostate cancer.
- Histopathological analysis confirmed the rectal lesion was metastatic prostate cancer in the rectal adventitia.
- The case emphasizes the importance of considering prostate cancer metastasis in the differential diagnosis of rectal tumors.

## Abstract

Rectal metastases of prostate cancer are rare and may be difficult to diagnose. In this report, we describe a case in which an extramural growth-type rectal tumor was resected and pathologically diagnosed as prostate cancer metastasis. A 70-year-old man on hormone therapy for prostate cancer with seminal vesicle invasion and pelvic lymph node metastasis was referred to our department after an imaging scan showed an extramural growth-type rectal tumor. Endoscopic ultrasound-guided fine needle aspiration was considered for diagnosis, but the patient preferred an early resection without the exam, so surgery was performed. Histopathological examination revealed that the lesion was in the adventitia of the rectum and metastasis of prostate cancer. Metastatic lesions of prostate cancer are not indicated for resection. A detailed preoperative study with the possibility of prostate cancer metastasis in mind is necessary because it is relevant to choosing the treatment strategy.