This is a 55 year old lady undergoing flexible sigmoidoscopy to investigate her recurrent rectal prolapse. This polypoid lesion was found on retroverting the endoscope in the rectum. On the right is a close-up of the lesion. Four biopsies were taken from the lesion without difficulty.
What is the most likely histology?
- Fibro-epithelial polyp
- Inflammatory polyp
- Squamous cell carcinoma
The polyp is angry red, with normal small round crypts and a couple of superficial erosions (appear as specs of white mucus). Histology confirmed that this was an inflammatory polyp. You may ask how to correctly differentiate between this and a fibro-epithelial polyp? It’s simple – the patient will cry out aloud when you sink the teeth of your biopsy forceps into any rectal lesion covered with squamous mucosa.
Frequency: The peak incidence is within the fourth and seventh decades of life. Up to 90% of patients are women. Although multiple pregnancies are often implicated in the aetiology, 35% of patients are nulliparous.
Aetiology: The aetiology of rectal prolapse is unknown, but it is often associated with long-standing constipation. Other predisposing conditions include chronic straining during defecation, pregnancy, previous surgery, and neurological disease. The pathophysiology of rectal prolapse is also not completely understood or agreed upon.
The are two main theories:
- The rectal prolapse is a sliding hernia through a defect in the pelvic fascia.
- The rectal prolapse starts as a circumferential internal intussusception of the rectum beginning 6-8 cm proximal to the anal verge. With time and straining, this progresses to full-thickness rectal prolapse, although some patients never progress beyond this stage.
Certain anatomic features found during surgery for rectal prolapse are common to most patients. These features include a patulous or weak anal sphincter with levator diastasis, deep anterior Douglas cul-de-sac, poor posterior rectal fixation with a long rectal mesentery, and redundant rectosigmoid. Whether these anatomic features are the cause or result of the prolapsing rectum is not known. The condition is often concurrent with pelvic floor descent and prolapse of other pelvic floor organs such as the uterus or the bladder.
Clinical details: Three different clinical entities are often combined and called rectal prolapse: full-thickness rectal prolapse, mucosal prolapse, and internal prolapse (internal intussusception). Treatment of these 3 entities differs. Full-thickness rectal prolapse is the most commonly recognized type and is defined as protrusion of the full thickness of the rectal wall through the anus. In mucosal prolapse, only the rectal mucosa (not the entire wall) protrudes from the anus. Internal intussusception may be a full thickness or a partial rectal wall disorder, but the prolapsed tissue does not pass beyond the anal canal and does not pass out of the anus.
Patients with rectal prolapse report a mass protruding through the anus. Initially, the mass protrudes from the anus only after a bowel movement and usually retracts when the patient stands up. As the disease process progresses, the mass protrude more often, especially with straining and Valsalva manoeuvres such as sneezing or coughing. Finally, the rectum prolapses with daily activities such as walking and may progress to continual prolapse. In addition to a protruding mass from the anus, patients often report faecal incontinence.
Patients with mucosal prolapse have similar problems but not to the same degree. Mucosal prolapse typically exhibits radial folds of the protruding mucosa instead of the concentric rings of a full rectal prolapse.