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BMJ Case Rep. 2010; 2010: bcr08.2009.2169.
Published online 2010 January 13. doi:  10.1136/bcr.08.2009.2169
PMCID: PMC3027388
Reminder of important clinical lesson

Fibroepithelial polyp in an anal fistulous track: a sign of chronic pathology

Abstract

Hypertrophied anal papillae and fibroepithelial polyps are benign acquired polypoid lesions of the anal canal. The development and protrusion of a fibroepithelial polyp in an anal fistulous track is described. This is a rare physical sign of chronic anal pathology.

Background

Fibroepithelial anal polyps are considered to originate from the anal papillae, which are projections at the mucocutaneous junction of the upper anal canal that give the serrated appearance of the pectinate line on proctoscopy. When anal papillae become hypertrophic they may form fibroepithelial anal polyps.1 Hypertrophic papillae/fibroepithelial anal polyps are benign acquired lesions commonly encountered on proctoscopy; they are not usually associated with specific symptoms, although they have received scant research attention. An unusual clinical presentation is described in this case report.

Case presentation

A 38-year-old woman presented at the emergency department with a week’s history of anal pain and one-and-a-half years of vague anal discomfort, but no history of abscess formation or purulent discharge. A 2 cm palpable, painless lymph node was found in her right groin on physical examination. Adequate anal examination was not feasible and she was taken to the operating theatre for examination under anaesthesia. The physical examination was otherwise unremarkable.

On examination under anaesthesia, she seemed to have an increased anal sphincter tone; there were redundant skin tags all around the anus, which retraced into the anal canal, but they were most prominent between 3 and 9 o’clock; there was also a fistula-in-ano, but no signs of a chronic anal fissure (fig 1A). The external opening of the fistulous track was located at 6 o’clock and the internal opening at the same hour in the lower anal canal; the track was passing through the inferior third of the internal sphincter—that is, a type 1 anal fistula2 (fig 1B,C). A fibrous polyp with a long stalk based on the dentate junction was running along the fistulous track and protruded in the posterior anal region (fig 1B,C). The polyp was 2 cm and not reducible because its size was larger than the width of the fistulous track. No other pathology was revealed by proctoscopy and rectosigmoidoscopy.

Figure 1
(A) Redundant skin tags, most prominent between 3 and 9 o’clock, obscuring the fibroepithelial polyp. (B) The fibroepithelial polyp protruding from the external opening of the fistulous track on the external surface of the skin tag, which is retracted ...

The lymph node in the patient’s right groin was firstly removed for histology. Consequently, a fistulotomy, including excision of the medial wall of the fistulous track, was performed and the posterior anal redundant skin tag and the fibroepithelial polyp were excised en bloc. The wound was left open to heal. The postoperative course was uneventful and the perianal wound healed uneventfully in 4 weeks.

Histology of the 4.2×3.1×0.4 cm excised specimen with the 2 cm polyp confirmed the presence of remnants of a fistulous track with abandoned bundles of smooth muscle from the internal anal sphincter (fig 2A), and the presence of a fibroepithelial polyp with a collagenous stroma covered by squamous epithelium (fig 2B). The excised lymph node from the groin was 2.2×0.7 cm in size. Histology revealed a diffuse type reactive lymphadenopathy. Re-examination at 6 months and 3 years later was unremarkable.

Figure 2
(A) The diagnostic accuracy of the type of fistula is supported by the presence of smooth muscle bundles from the internal sphincter shown by the arrows in the histology of the specimen; microphotograph haematoxylin and eosin (H&E) ×100. ...

Discussion

The hypertrophic anal papillae and fibroepithelial polyps are benign lesions consisting of myxoid or collagenous stroma covered by squamous epithelium. They contain mononucleated and multinucleated stromal cells with fibroblastic and myofibroblastic differentiation, and mast cells.3 The occurrence of stromal atypia usually encountered in large size hypertrophic anal papillae/fibroepithelial polyps is considered to be reactive or reparative.4 Awareness of stromal atypia will reduce the likelihood of the misinterpretation of these lesions as malignant tumours. With respect to aetiology, hypertrophic anal papillae and fibroepithelial polyps are considered as a hypertrophic response of the modified anoderm in the region of the anal columns to irritation, injury or infection.35

The authors’ interpretation of the physical findings presented here is that a low inter-sphincteric cryptoglandular abscess gave rise to a low type 1 inter-sphincteric fistula-in-ano,2 which was followed by the development and prolapse of a fibroepithelial polyp. The diagnostic accuracy of the type of fistula is supported by the presence of smooth muscle bundles from the internal sphincter in the histology of the specimen (fig 2A). As its size was larger than the diameter of the fistulous track, it is concluded that the polyp developed up to this size while it was outside the anal canal. However, the development of fibroepithelial polyps in anal fistulae is rarely described. Moreover, the lack of history of abscess formation indicates that the stalk of the polyp could have been functioning as a natural seton, keeping the fistulous track open, facilitating drainage, and prohibiting recurrent abscess formation.2,6

On the other hand, fibroepithelial polyps are commonly associated with chronic anal fissures. The patient’s history was more consistent with a chronic anal fissure. Hence, the fistulous track may represent a healing process from the edges of an anal fissure—that is, a “healed over” anal fissure that resulted in the fistulous track. In either case, the presented physical signs indicate a response to chronic anal pathology.

The hypertrophic anal papillae and fibroepithelial polyps may prolapse, bleed and cause anal discomfort, but are not usually associated with specific symptoms or with chronic idiopathic pruritus ani.7,8 Symptomatic as well as large anal papillae and fibrous anal polyps should be removed and examined histologically. The removal of hypertrophied anal papillae and fibrous anal polyps has also been recommended during the surgical treatment of chronic fissure-in-ano.9

In conclusion, the development and protrusion of a fibroepithelial polyp in an anal fistulous track is described. This is a rare physical sign indicating chronic anal pathology.

Learning points

  • Increased anal sphincter tone, redundant anal skin tags and anal pain render physical examination inconclusive and necessitate examination under anaesthesia.
  • Reactive inguinal lymphadenopathy may accompany benign anal pathology.
  • Fibroepithelial anal polyps represent a hypertrophic response to irritation, injury or infection that accompanies an anal fistulous track.
  • Fibroepithelial anal polyp is a physical sign indicating chronic anal pathology.

Footnotes

Competing interests: None.

Patient consent: Patient/guardian consent was obtained for publication.

REFERENCES

1. Goligher J, Duthie H, Nixon H. Surgery of the anus rectum and colon, 5th edn London: Bailliere Tindall, 1992.
2. Parks AG, Gordon PH, Hardcastle JD. A classification of fistula-in-ano. Br J Surg 1976; 63: 1–12. [PubMed]
3. Groisman GM, Polak-Charcon S. Fibroepithelial polyps of the anus: a histologic, immunohistochemical, and ultrastructural study, including comparison with the normal anal subepithelial layer. Am J Surg Pathol 1998; 22: 70–6. [PubMed]
4. Schinella RA. Stromal atypia in anal papillae. Dis Colon Rectum 1976; 19: 611–13. [PubMed]
5. Schutte AG, Tolentino MG. A second study of anal papillae. Dis Colon Rectum 1971; 14: 435–50. [PubMed]
6. Malik AI, Nelson RL. Surgical management of anal fistulae: a systematic review. Colorectal Dis 2008; 10: 420–30. [PubMed]
7. Lenhard B. [Guideline on the disease picture of hypertrophic anal papilla]. Hautarzt 2002; 53: 104–5. [PubMed]
8. Jensen SL. A randomised trial of simple excision of non-specific hypertrophied anal papillae versus expectant management in patients with chronic pruritus ani. Ann R Coll Surg Engl 1988; 70: 348–9. [PMC free article] [PubMed]
9. Gupta PJ. Hypertrophied anal papillae and fibrous anal polyps, should they be removed during anal fissure surgery? World J Gastroenterol 2004; 10: 2412–4. [PubMed]

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