Visual guide
An educational, non-diagnostic guide to how Acne Inversa / HS may appear across different body areas, stages, and skin tones — explained in plain language.
Hidradenitis suppurativa may cause recurring deep lumps, inflamed areas, drainage, tunnels beneath the skin, and scarring. It can affect different body areas and may appear differently across skin tones.
These illustrations are provided for education only. HS cannot be diagnosed from an image alone, and other skin conditions can look similar. If you have recurring painful lumps, drainage, or scarring, consider discussing them with a dermatologist or another qualified healthcare professional.
HS is not caused by poor hygiene and it is not contagious.
This guide currently uses schematic medical-style illustrations rather than clinical photographs. Licensed, consented clinical photographs will only be added after image rights and medical review are documented — and will then stay hidden until you actively choose to view them.
HS commonly develops where skin touches or rubs against skin, but less common locations are also possible. Choose a body area to jump to matching examples.
Front
Back
One of the most common sites: skin rests on skin and rubs with movement.
The fold beneath the breast is a typical area where skin touches skin.
Friction from walking and clothing makes this region especially commonly affected.
A sensitive but medically important area — raise it openly at appointments.
Prolonged sitting and pressure can make symptoms here more bothersome.
Changes can also keep returning where waistbands or belts rub.
Less often affected but possible — HS is often not suspected here.
Occasional lesions outside the classic skin folds do occur.
For example the scalp or the area around the navel. HS is not limited to a fixed list of locations.
Not sure about body areas? Start from what you see or feel. Selecting a description highlights matching examples.
One of the most common sites: skin rests on skin and rubs with movement.
Armpits
Visible features: A raised, taut area with surrounding inflammation. On darker skin, inflammation may look deep brown, violet, or greyish rather than red.
What someone may notice: It may feel tender or painful beneath the skin — often before much is visible. Appearance and symptoms vary between people.
Medical term: A clinician may describe this as an inflammatory nodule.
This image cannot confirm a diagnosis.
Armpits
Visible features: Several raised areas of different sizes close together, some with reddened or discoloured surroundings.
What someone may notice: Individual lumps may settle and return weeks or months later in the same or a neighbouring spot. This recurring pattern is an important point to raise with a clinician.
Medical term: Recurring inflammatory nodules in typical areas are a core feature clinicians ask about when considering HS.
This image cannot confirm a diagnosis.
Armpits
Visible features: Rope-like, thickened bands of scar tissue across the skin fold, sometimes with indented areas.
What someone may notice: The skin may feel tight or pull when raising the arm. Structural changes like this are a reason to discuss treatment options with a clinician.
Medical term: Reports sometimes describe these as rope-like or hypertrophic scars.
This image cannot confirm a diagnosis.
Armpits
Visible features: Several openings and cord-like ridges; beneath the surface, tracts connect the affected sites (shown here in cross-section).
What someone may notice: Intermittent drainage, tightness, and repeated inflammation in the same area. At this stage, specialist care is especially important.
Medical term: Extensive tracts with scarring feed into clinical severity staging (for example the Hurley stage).
This image cannot confirm a diagnosis.
The fold beneath the breast is a typical area where skin touches skin.
Under or around the breasts
Visible features: A raised, inflamed area with a small opening from which fluid may drain.
What someone may notice: Drainage can stain clothing and may have an odour. This is a known consequence of the condition — not a hygiene problem.
Medical term: A clinician may describe a collection like this as an abscess.
This image cannot confirm a diagnosis.
Under or around the breasts
Visible features: Small dark dots, often appearing in pairs, along with fine pitted indentations.
What someone may notice: These changes are often painless but can be a clue to earlier inflammation in the area.
Medical term: Paired blackheads are known medically as double comedones and are considered a typical HS clue.
This image cannot confirm a diagnosis.
Friction from walking and clothing makes this region especially commonly affected.
Groin and inner thighs
Visible features: A single raised area in the groin crease. On deeply pigmented skin, the swelling is often more noticeable than any redness.
What someone may notice: Walking, sitting, or tight clothing can make the pain worse. Many people initially mistake these lumps for ingrown hairs or boils.
Medical term: The medical term is again usually an inflammatory nodule; with a pus collection, an abscess.
This image cannot confirm a diagnosis.
Groin and inner thighs
Visible features: From the outside, often just two small openings or a cord-like ridge; the connection runs beneath the surface (shown here in cross-section).
What someone may notice: Pressing on one spot may release fluid from another. Tunnels rarely heal on their own and are an important finding for a clinical examination.
Medical term: Clinicians call these sinus tracts or fistulas.
This image cannot confirm a diagnosis.
A sensitive but medically important area — raise it openly at appointments.
Specifically about the vulva: recurring lumps, Bartholin cysts, and other causes
Genital and perianal area
Visible features: Inflamed raised areas with small openings that intermittently release fluid.
What someone may notice: Many people hesitate to mention this region out of embarrassment. Dermatologists know this location well — describing it openly helps them assess it.
Medical term: Reports may mention perianal abscesses or draining sinus tracts.
This image cannot confirm a diagnosis.
Prolonged sitting and pressure can make symptoms here more bothersome.
Buttocks
Visible features: Grouped raised areas, some freshly inflamed, some settling with darker discolouration.
What someone may notice: Sitting can be painful. Settling lesions can leave darker marks that persist longer on more pigmented skin (post-inflammatory hyperpigmentation).
Medical term: Several lumps in one area are often described as grouped inflammatory lesions.
This image cannot confirm a diagnosis.
Buttocks
Visible features: Thickened or indented scar areas and small pitted marks where earlier inflammation has healed.
What someone may notice: Scars are often painless, but they document the history of the condition — useful information for clinical assessment and staging.
Medical term: Depending on their form, these are called hypertrophic (raised) or atrophic (sunken) scars.
This image cannot confirm a diagnosis.
Changes can also keep returning where waistbands or belts rub.
Abdominal folds and waistband
Visible features: One active lump beside faint traces of earlier flare-ups in almost the same spot.
What someone may notice: Friction from a waistband or belt can aggravate flares here. The pattern of returning to the same spot is what distinguishes HS from an ordinary one-off boil.
Medical term: Clinicians specifically ask about recurrent lesions at the same location.
This image cannot confirm a diagnosis.
Less often affected but possible — HS is often not suspected here.
Neck and behind the ears
Visible features: Small dark dots, some paired, and occasional small raised areas.
What someone may notice: Because this region seems unusual, HS here is often mistaken for acne. Mention at appointments if typical areas like the armpits or groin are also affected.
Medical term: Double comedones and small inflammatory nodules can be described here as well.
This image cannot confirm a diagnosis.
Occasional lesions outside the classic skin folds do occur.
Chest and back
Visible features: Single or few raised, inflamed areas outside the classic skin folds.
What someone may notice: These lesions can occur alongside changes in typical areas. A photo diary of flares can help your care team.
Medical term: Distinguishing HS from acne or another condition here is a job for a clinician.
This image cannot confirm a diagnosis.
For example the scalp or the area around the navel. HS is not limited to a fixed list of locations.
Other less common areas
Visible features: An inflamed lump with traces of earlier episodes in the immediate surroundings.
What someone may notice: The scalp or navel area can also be affected. Unusual locations contribute to diagnosis taking many years on average — which makes your own observations valuable.
Medical term: For atypical sites, clinicians check especially carefully whether HS or another condition explains the findings.
This image cannot confirm a diagnosis.
Some HS lesions change over weeks or months. This simplified sequence shows one possible pattern.
HS does not always follow this sequence. Many lumps settle without draining or scarring — this illustration shows one possible pattern, not a prediction.
On lighter skin, inflammation often looks pink or red. On darker skin, the same inflammation may appear deep brown, violet, or greyish — and redness can be easy to miss. Swelling, warmth, tenderness, and a recurring pattern are important clues on every skin tone.
After lesions settle, darker skin may show longer-lasting dark marks (post-inflammatory hyperpigmentation) and more visible scarring. The examples throughout this guide are deliberately drawn on a range of skin tones rather than collected in a separate section.
Several conditions can resemble HS, which is one reason diagnosis is often delayed. Only a clinical examination can tell them apart.
Usually occur singly and in changing spots; HS typically keeps returning to the same areas.
Mainly affects the face, chest, and back; HS favours skin folds like the armpits and groin.
More superficial and usually short-lived; HS lumps sit deeper and persist longer.
Single cysts usually stay localised; HS often produces multiple lesions and tunnels.
Typically sits over the tailbone; it can, however, occur alongside HS.
Forms at one of the Bartholin glands beside the vaginal opening and is usually one-sided; HS more often shows a recurring pattern across several hair-bearing areas. The two can also occur together.
Consider speaking with a dermatologist or another qualified healthcare professional if you experience recurring painful lumps, drainage, wounds that heal slowly, scarring, or repeated symptoms in areas where skin touches skin.
Seek prompt medical care if you feel acutely unwell, develop fever, have rapidly spreading redness or swelling, or are concerned about a serious infection.
Yes. On lighter skin, inflammation often looks pink or red. On darker skin it may appear deep brown, violet, or greyish, and redness can be hard to see. Settling lesions can leave darker marks that last longer on more pigmented skin. Swelling, pain, and recurrence are important clues on every skin tone.
Yes. HS most often develops where skin touches skin — such as the armpits, groin, the fold under the breasts, the buttocks, and the genital area. Less commonly, the neck, scalp, navel area, or other sites can be affected.
No. Several skin conditions can look very similar. Diagnosis relies on a clinical examination and your history — especially typical locations and a recurring course. Images can, however, help you describe what you have observed.
For example boils, severe acne, ingrown hairs, inflamed cysts, or a pilonidal sinus. One important difference: HS typically keeps returning to the same areas over months. Telling them apart is a job for a clinician.
It can help, because flares may have settled by the time of your appointment. Dated photos plus notes on location, pain, and duration help your care team assess the course. Store such images securely and share them only with your care team.
No. Some lumps settle without draining or scarring. Others progress. The course is individual — one more reason early clinical care is worthwhile.