Background

A 32-year-old female patient, primiparous, with no particular pathological history, presented a painful cutaneous nodule located at the perianal level of the left buttock evolving since her delivery 3 years ago, and through which seropurulent fluid flows intermittently. The symptomatology evolved in a context of apyrexia and conservation of the general state. It was treated many times as an abscess by oral antibiotherapy with no total remission. She has no digestive symptoms. Clinical examination found an erythematousdermo-epidermal nodule of renitant consistency measuring 1 cm, with a whitish satellite swelling measuring 0.5 cm. The perilesional skin was flesh-colored and retractile. Examination of the lymph node areas didn’t find palpable lymphadenopathy. Skin biopsy showed non-specific fibrous dermatitis. The soft tissue ultrasound revealed an anal fistula unclogging to the skin. The patient was referred to the gastroenterology department for specialized care of her anal fistula which was cryptoglandular. A fistulectomy was planned.

The originality of our observation lies in the fact that the diagnosis of anal fistula remained unknown for a long time despite its evidence. Our patient was treated for 3 years by general practitioners as a pyogenic abscess without doing further explorations, until we discovered the presence of an underlying anal fistula. It is therefore essential to make practitioners aware of this entity. Any cutaneous nodule in the gluteal region should raise suspicion of an underlying digestive tract damage [2]. The positive diagnosis requires radiological investigations mainly Magnetic resonance imaging [3]. The etiology of anal fistulas can be cryptoglandular as the case of our patient, Crohn’s disease, tuberculosis, trauma, or rectal cancer [4]. The differential diagnoses are pyogenic abscesses, pilonidal sinus, hidradenitis suppurativa, or suppurating skin cyst [1]. The treatment is interventional with a high risk of recurrence [5].

Figure 1: Image showing anal fistula.

References

1. Jimenez M, Mandava N. Anorectal Fistula. 2021 Sep 27. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan–. PMID: 32809492.
2. Fitzpatrick, James E., and Lori Prok. “Dermatologic Manifestations of Gastrointestinal Disease.” GI/Liver Secrets. Mosby, 2010. 464-469.
3. Fernandez P, Abramowitz L. Description et intérêt de l’IRM dans le cadre des fistules anopérinéales. HepGastrOncolo Dig. 2007;14(4):257-264.
4. García-Olmo D, Van Assche G, Tagarro I, Diez MC, Richard MP, Khalid JM, van Dijk M, Bennett D, Hokkanen SRK, Panés J. Prevalence of Anal Fistulas in Europe: Systematic Literature Reviews and Population-Based Database Analysis. AdvTher. 2019; 36(12): 3503-3518.
5. Senéjoux, A. Prise en charge des fistules anales cryptogénétiques. Traitement conventionnel. Côlon & Rectum. 2007; 1(2): 87–92.