Symptoms and diagnosis of hidradenitis suppurativa

What are the first signs of hidradenitis suppurativa?

Hidradenitis suppurativa shows as painful nodules and abscesses, which can go on to discharge pus, form small tunnels under the skin (fistulas) and leave scars [SFD].

What do the lesions look like?

The inflammatory lesions are painful, red to purplish, and come in flares [SFD]:

• The nodule: a firm, red lump under the skin, more than one centimetre across, painful on its own or when pressed.
• The abscess: pus forms in the nodule, which becomes soft to the touch. It can open onto the skin by itself or after an incision.
• The papule and the pustule: a small red raised spot of less than one centimetre, or a small spot containing yellow pus.
• The tunnel (also called a fistula, sinus or sinus tract): a channel under the skin that lets fluid drain out, by itself or when pressed. When several tunnels are connected, the fluid drains through several openings.

Other lesions are neither red nor painful: blackheads, sometimes with several pores, painless nodules after a flare, and scars [SFD]. The scars can be thick and rope-like [sheet].

What is a flare?

A flare is an acute inflammatory episode, on an old or a new lesion, with pain and redness, with or without discharge of pus [sheet]. Flares are more or less spaced out, or occur against a continuous background [SFD].

Their repetition matters for the diagnosis: one of the three criteria is having had at least 2 flares in 6 months (see the diagnostic criteria). Noting the date and location of each flare helps the doctor.

Where do the lesions of hidradenitis suppurativa appear?

The lesions appear mainly in the perineal area and the large skin folds of the body: armpits, groin and the folds under the breasts [sheet].

The typical locations are [SFD] [sheet]:

• the armpits;
• the groin folds;
• the area around the anus and the perineum;
• the breasts and the folds under the breasts;
• the fold between the buttocks and the buttocks;
• the pubic area.

Lesions can also appear in areas exposed to repeated friction, such as the nape of the neck, behind the ear or the abdomen [sheet].

For doctors, any nodule, cyst or abscess located in the armpits, groin, perineum or breasts should bring hidradenitis suppurativa to mind [SFD].

How does hidradenitis suppurativa progress?

Hidradenitis suppurativa is a chronic disease: it progresses in flares, and its severity is assessed area by area, most often with the Hurley classification [SFD] [34].

What are the three Hurley stages?

The Hurley stage is determined for a given area of the body [sheet]. For everyday practice, the Société Française de Dermatologie (SFD, the French Society of Dermatology) recommends simple tools such as this classification [SFD].

1. I Stage I: one or more abscesses, without spread under the skin, without tunnels and without scars.
2. II Stage II: abscesses that come back, separated by areas of healthy skin, with tunnels that are not connected to each other and thick scars.
3. III Stage III: diffuse or almost diffuse involvement, with no area of healthy skin, with interconnected tunnels and abscesses across the whole area.

Descriptions based on the Hurley classification [34], as presented in the SNFCP summary sheet [sheet].

How does the doctor monitor progress?

Other scores count the inflammatory lesions and the tunnels, which makes it possible to follow the course of the disease over time [sheet]:

• The IHS4 score adds up, over the whole body, the number of nodules (1 point each), abscesses (2 points) and tunnels (4 points). A total of 3 points or fewer corresponds to mild disease, 4 to 10 points to moderate disease, and 11 points or more to severe disease [36].
• The modified Sartorius score takes into account the areas affected, the number and type of lesions, and the distance between the most significant lesions [35].
• The HiSCR score is used to judge the response to a treatment: it is achieved when the number of inflammatory lesions (abscesses and nodules) falls by at least 50%, with no increase in the number of abscesses or tunnels [37].

These scores are calculated by the doctor during the examination.

Does the disease always take the same form?

No. Doctors describe six forms, or phenotypes, of hidradenitis suppurativa [33]:

• the classic form;
• a form with many nodules and abscesses in areas of friction (abdomen, thighs, buttocks), in people who are overweight;
• a form with pustules, cysts, superficial nodules, small pitted scars and double-pored blackheads (buttocks, groin, pubic area), in people who are overweight and smoke;
• a form with cysts and severe acne of the back and face (conglobata form);
• a form that affects the face (ectopic form);
• a form associated with other inflammatory diseases (syndromic form).

Why report a lesion that changes in appearance?

A few observational studies have shown a risk of squamous cell carcinoma, a skin cancer, that is about 4 times higher in people with hidradenitis suppurativa [40] [41]. It has mainly been seen in men with long-standing disease, of more than 10 to 20 years, with lesions of the perineum and buttocks [sheet].

This is why any lesion that changes in appearance should be shown to the doctor, who may take a biopsy [sheet].

How does the doctor diagnose hidradenitis suppurativa?

The diagnosis of hidradenitis suppurativa is clinical: it is based on the combination of three criteria adopted by the Société Française de Dermatologie, and no additional test is needed [SFD].

1. 1 Painful nodules and abscesses, which go on to discharge pus, form tunnels and/or leave scars.
2. 2 Typical locations: armpits, groin folds, area around the anus and/or perineum, breasts and folds under the breasts, fold between the buttocks, pubic area.
3. 3 A chronic and recurring course: at least 2 flares in 6 months.

All three criteria must be present for a definite diagnosis. The SNFCP summary sheet describes the same criteria and links them to an international conference on the disease (HS Foundation, San Francisco, 2009) [sheet].

What can support the diagnosis?

Other elements can support the diagnosis [sheet]:

• cases of hidradenitis suppurativa in the family, found in about 1/3 of cases [6];
• inflammatory lesions that are less typical, but that come back in a typical location;
• a history of pilonidal sinus (a cavity under the skin of the fold between the buttocks, which can become infected).

Is a test sometimes useful?

No sample is needed to confirm hidradenitis suppurativa. A test can, however, help to rule out another condition or to assess the lesions better [sheet]:

• A sample of pus makes it possible to rule out boils caused by Staphylococcus aureus bacteria.
• A biopsy may be taken if a lesion changes in appearance, especially after the age of 50 in a person who has had lesions of the perineum for more than 20 years.
• Imaging (ultrasound, CT scan, MRI) can show the extent of the lesions and their activity, which examination of the skin alone can underestimate, particularly in the perineum and buttocks. MRI also helps to avoid missing an anal fistula [31].

Why is the diagnosis often late?

The delay between the first symptoms and the diagnosis is about 8 years, according to the French R-ENS Verneuil study, which looked at misdiagnosis of the disease [2]. The diagnosis is clinical but can sometimes be difficult to make [sheet]: other conditions can resemble hidradenitis suppurativa (see the conditions to rule out).

Which conditions can hidradenitis suppurativa be mistaken for?

Several conditions also cause repeated abscesses or chronic discharge. The question arises mainly when the lesions are few (stage I) or located near the anus and buttocks [sheet]. It is for the doctor to tell them apart.

What are the main conditions to rule out?

• Staphylococcal skin infections, such as boils: this is the main condition to rule out. The lesions more often contain pus, more often have areas of dead skin (necrosis), follow one another very quickly and appear in more varied places. A sample that finds Staphylococcus aureus confirms the diagnosis [sheet].
• Perianal abscess (abscess of the anal margin): this is the most common cause of pus discharge in the perineum (about 70%). It most often comes from infection of a gland of the anus [sheet].
• Crohn’s disease with lesions around the anus: it can be difficult to distinguish from hidradenitis suppurativa, especially as the two diseases can exist at the same time [sheet]. Inflammatory bowel diseases should be considered when hidradenitis suppurativa affects only the perineum [SFD].
• Infected skin cysts: lumps under the skin, topped by a small opening, with white or yellowish contents. They often come to light during an infection [sheet].
• Steatocystoma multiplex: a condition that begins after puberty, with cysts in the armpits, on the front of the chest or on the upper back, often on both sides. A biopsy confirms the diagnosis [sheet].

Which other conditions may the doctor consider?

The Société Française de Dermatologie also lists [SFD]:

• other diseases of the skin glands: acne conglobata, pilonidal sinus, Bartholin’s gland cyst, fistulas present from birth;
• certain infections: abscesses, carbuncles, boils, actinomycosis, cat-scratch disease, donovanosis, lymphogranuloma venereum, syphilis and tuberculous abscesses.

Where to seek care?

If you recognise these signs, talk to your general practitioner or a dermatologist.

The Seeing a doctor page explains which doctor to see and how to find a dermatologist, and offers a questionnaire to prepare for your consultation.

For the management options, read Treatments for hidradenitis suppurativa.

What are the sources for this page?

The information on this page comes from the summary sheet “Maladie de Verneuil – Épidémiologie” (SNFCP, 2024), the studies it cites and the guidelines of the Société Française de Dermatologie.

[sheet] Ezanno AC, Fougerousse AC, Alam A. Maladie de Verneuil – Épidémiologie. Diplôme inter-universitaire de proctologie médicochirurgicale, SNFCP, 2024.

[SFD] Société Française de Dermatologie, Centre de Preuves en Dermatologie. Recommandations hidradénite suppurée (hidradenitis suppurativa guidelines, 2019 update): pages “Diagnostic de l’hidradénite suppurée” (updated 19 January 2026), “Lésions élémentaires” and “Évaluation de la sévérité”.

Studies cited by the summary sheet and used on this page, with their original number:

2. Loget J, Saint-Martin C, Guillem P, Kanagaratnam L, Becherel PA, Nassif A, et al. [Misdiagnosis of hidradenitis suppurativa continues to be a major issue. The R-ENS Verneuil study]. Ann Dermatol Venereol. 2018 May;145(5):331–8. Search on PubMed
6. Zouboulis CC, Desai N, Emtestam L, Hunger RE, Ioannides D, Juhász I, et al. European S1 guideline for the treatment of hidradenitis suppurativa/acne inversa. J Eur Acad Dermatol Venereol JEADV. 2015 Apr;29(4):619–44. Search on PubMed
31. Gutfilen-Schlesinger G, Lopes de Souza SA, Gutfilen B. Should We Scan Hidradenitis Suppurativa Patients? A Systematic Review of Radiologic Findings. Adv Skin Wound Care. 2021 Jul 1;34(7):1–10. Search on PubMed
33. van der Zee HH, Jemec GBE. New insights into the diagnosis of hidradenitis suppurativa: Clinical presentations and phenotypes. J Am Acad Dermatol. 2015 Nov;73(5 Suppl 1):S23-26. Search on PubMed
34. Hurley H. Dermatological surgery: principles and practice. New York, NY: Marcel Dekker. 1989.
35. Revuz J. [Modifications to the Sartorius score and instructions for evaluating the severity of suppurative hidradenitis]. Ann Dermatol Venereol. 2007 Feb;134(2):173–4. Search on PubMed
36. Zouboulis CC, Tzellos T, Kyrgidis A, Jemec GBE, Bechara FG, Giamarellos-Bourboulis EJ, et al. Development and validation of the International Hidradenitis Suppurativa Severity Score System (IHS4), a novel dynamic scoring system to assess HS severity. Br J Dermatol. 2017 Nov;177(5):1401–9. Search on PubMed
37. Kimball AB, Sobell JM, Zouboulis CC, Gu Y, Williams DA, Sundaram M, et al. HiSCR (Hidradenitis Suppurativa Clinical Response): a novel clinical endpoint to evaluate therapeutic outcomes in patients with hidradenitis suppurativa from the placebo-controlled portion of a phase 2 adalimumab study. J Eur Acad Dermatol Venereol JEADV. 2016 Jun;30(6):989–94. Search on PubMed
40. Shlyankevich J, Chen AJ, Kim GE, Kimball AB. Hidradenitis suppurativa is a systemic disease with substantial comorbidity burden: a chart-verified case-control analysis. J Am Acad Dermatol. 2014 Dec;71(6):1144–50. Search on PubMed
41. Lapins J, Ye W, Nyrén O, Emtestam L. Incidence of cancer among patients with hidradenitis suppurativa. Arch Dermatol. 2001 Jun;137(6):730–4. Search on PubMed

The figures on how common the disease is, its causes and associated conditions are on the home page, with their sources.