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Background
Mucoceles are commonly associated with the appendix, gall bladder and cranial sinus, 1 and are extremely rare in the rectum. Rectal mucoceles are presumed to develop secondary to invasion of the mucous membrane of the rectum by an intervention or obstruction of the anal gland. In this report, we describe a case of a rectal mucocele that developed in the anterior wall of the rectum after a haemorrhoidectomy.
Case presentation
An 84-year-old man presented to our hospital in 2015 with a mass prolapsing from his anus.
Previous medical history
The patient had undergone a haemorrhoidectomy in 1964. Based on our rectal examination, we speculated that the haemorrhoidectomy had been performed using Whitehead's procedure.
The patient first presented to our hospital in 2004 for treatment of an anal fissure and sphincter insufficiency. The symptom was considered to have resulted from haemorrhoidectomy, and conservative treatment was carried out. Because the patient recovered with conservative treatment, image examination was not enforced.
The patient was diagnosed with ascending colonic diverticulitis by CT imaging in 2006. At that time, a rectal mucocele was not pointed out definitely.
History of present illness
In May 2009, he reported a sense of discomfort in his anus and difficulty urinating. Physical rectal palpation revealed an elastic soft mass in the anterior wall of the rectum, with a normal mucous membrane. He underwent further examination for a suspected rectal submucosal tumour. CT imaging revealed a lower rectal submucosal cyst ( figure 1A ). A lower rectal endoscopic examination and MRI revealed that the interior of the cyst was uniform, with a watery consistency and absence of nodule formation. As per our hospital guidelines, the patient was followed up for observation. In January 2015, the cyst began prolapsing from the anus.
Family history
The family history was unremarkable.
Investigations
Current disease
At the time of admission, the patient was 159.9cm tall, with a weight of 54.0kg. Digital rectal and proctoscopy examination confirmed a soft and elastic mass in the anterior wall of the rectum, with no abnormality of the surrounding mucosa.
Blood test findings
All blood tests were normal, including tumour marker values.
Lower digestive tract endoscopy examination
A bulging lesion was identified on the anterior wall of the rectum, 1.5cm from the dentate line,...