PMC6522770_01
Magnetic resonance imaging shows a unilocular cystic tumor with a high signal intensity on T2-weighted images in the pelvis. (a) A well-defined homogeneous cystic mass is located in the left dorsal side of the rectum (arrow head) and (b) ventral side of the coccyx (arrow).
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T1-weighted images, high signal intensity on T2-weighted images, and high signal intensity on diffusion-weighted images (Fig. 1). The tumor was diagnosed as a developmental cyst based on the radiological findings, and laparoscopic resection was performed.
Laparoscopic findings in the pelvic cavity. (a) The arrow indicates the tumor, which is located on the left side of the rectum (arrowhead). (b) The arrow indicates the retrorectal epidermoid cyst as a retroperitoneal tumor. (c) The epidermoid cyst is a well-defined lesion, and ablation between the tumor and surroundings was easy to perorm.
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The tumor was placed along the left lateral side of the rectum (Fig. 2(a)). When the peritoneum was incised, a capsulated tumor was observed, and the caudal side of the tumor continued up to the level of the levator -ani (Fig. 2(b)). Resection around the whole circumference of the tumor was performed by using the Harmonic and the electric scalpel without adhesion to the surroundings (Fig. 2(c)).
Histopathological findings of the resected tumor. (a) The specimen measures 60 x 50 mm, and it is well circumscribed and soft. (b) The cut section of the gross specimen shows a thin-walled cyst filled with yellowish-colored gelatinous materials. (c) Microscopic findings show that the wall of cyst is lined with stratified squamous epithelia with cutaneous appendages.
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Microscopically, the inner surface of the cyst was lined with stratified squamous epithelia (Fig. 3(a)-(c)).