# Squamous Cell Carcinoma Originating from a Dermoid Cyst Located between the Upper Rectum and Prostate: A Case Report

## TL;DR

This case report describes a rare instance of squamous cell carcinoma that originated from a dermoid cyst in the pelvic area of a 46-year-old man.

## Contribution

The paper presents the first documented case of SCC arising from a dermoid cyst in the anterior rectal area.

## Key findings

- The cancer originated from a dermoid cyst and directly invaded the seminal vesicle.
- Robotic-assisted surgery enabled precise management and avoided cancer dissemination during the procedure.
- Pelvic dermoid cyst-derived SCC is rare but highly malignant and difficult to diagnose preoperatively.

## Abstract

Pelvic squamous cell carcinoma (SCC) originating from a dermoid cyst (DC) is extremely rare. Here, we report the first case of SCC that developed in the anterior rectal area.

A 46-year-old man was initially diagnosed with rectal SCC by endoscopic biopsy, and multimodal image findings demonstrated direct invasion of the urinary system. Accordingly, total pelvic exenteration with bilateral lymph node dissection was performed with robotic assistance, and the patient was discharged without severe postoperative complications. Histological assessment revealed that the cancer originated in a DC with direct invasion of the seminal vesicle.

Pelvic DC–derived SCC is rare but possesses high malignant potential. Because of the difficulty in preoperative diagnosis, diagnostic excision may be selected if complete resection is possible. Importantly, robot-assisted surgery enables precise management and might be an optimal strategy for preventing cancer dissemination by rupture during surgery.