Which factors are suggestive of hidradenitis suppurativa in patients with pilonidal sinus disease? Results from a 459 cross-sectional prospective study

Hidradenitis suppurativa in patients with pilonidal sinus disease

  • Farida Benhadou Department of Dermatology, Erasme Hospital, Université Libre de Bruxelles, Brussels, Belgium
  • Axel Patrice Villani
  • Philippe Guillem
Keywords: hidradenitis suppurativa, pilonidal sinus


In a recent international multicenter study performed on the behalf of the European Hidradenitis Suppurativa Foundation, we reported the high prevalence (27%) of inflammatory lesions in the intergluteal fold (pilonidal sinus disease – PSD – in 77%) in patients with hidradenitis suppurativa (HS). Although the exact underlying mechanisms are not understood, we also showed evidence that HS patients with PSD have a specific phenotype associating smoking, more severe HS and frequent disease occurrence in the breast, the buttocks, and in genital and anal regions. In the present study, we aimed to compare the clinical characteristics of patients operated for HS-free PSD and HS-associated PSD.
The next step of our work was to compare the clinical characteristics of patients operated for HS-free PSD and HS-associated PSD.

We prospectively included all consecutive patients who 1) underwent surgery in our secondary/tertiary center (Clinique du Val d’Ouest, Lyon, France) for inflammatory lesions in the intergluteal fold, and 2) had a definitive pathological diagnosis of PSD (patients operated for an inflammatory lesion in the intergluteal fold and with an actual pathological diagnosis of HS were excluded). Clinical and pathological data were recorded. Normality of the distributions was checked using a combination of Skewness and Kurtosis tests. Comparisons were performed using Student’s t test for continuous variables and Chi-squared test (gender, smoking, PSD recurrence, family history) and Fisher exact test (inflammatory comorbidities and acne conglobata) for categorical variables.

459 patients were included, 118 (26%) with and 341 (74%) patients without associated HS (Table 1). Patients with HS-associated PSD were significantly younger at surgery (25 vs 28 years), more frequently women (51% vs 34%), and smokers (75% vs 47%). They had a higher BMI (26 vs 24 kg/m2) and more frequently a medical history of inflammatory joint diseases (4% vs 1%) and acne conglobata (3% vs 0%). They also had more frequently a family history of HS (25% vs 4%) and a family history of “dermal swelling” (21% vs 4%; as defined by the patient, without any medical indication about the exact nature of the swelling: simple cyst, boil, abscess …).

Age at PSD occurrence was not different between the two groups in this univariate analysis. When associated with HS, PSD had longer dimensions (Table 1) and was more frequently recurred at the time of surgery (44% vs 29%).

Using logistic regression analyses, we identified age at surgery, female gender, BMI, smoking, family history of HS, and family history of dermal swelling as independent positive predictors of an HS-associated PSD (Table 1). Age at PSD occurrence proved to be an independent negative predictor of an HS-associated PSD.

PSD is a frequent clinical condition. The frequent and non-coincidental association of PSD and HS, as well as the fact that PSD can be the first occurring inflammatory skin lesion in HS patients (in up to 36% of the patients), raise the question of an associated HS. The physician facing a PSD should be aware of this possibility and should specifically look for HS through a complete physical examination (gender, age, BMI, other obvious inflammatory skin lesion) and by directly questioning the patient about his/her habits (smoking), his/her medical history (“have you ever experienced any kind of inflammatory lesion elsewhere in your body?”) and his/her family history. The discovery of any factor among those here found to be associated with an increased risk of HS should be accompanied by a specific follow-up or at least specific information delivered to the patient and/or his/her GP.