Resources · Hidradenitis suppurativa glossary
Plain language for living with HS
Hidradenitis suppurativa glossary
Twenty-seven concise definitions for terms found in HS appointments, articles, and patient conversations. This glossary explains words. It does not interpret records or replace a healthcare professional.
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7 paths · 27 entries
01Understanding HS language 3 entries
- 01
Hidradenitis suppurativa is a chronic inflammatory skin disease that can cause deep nodules, abscesses, drainage, tunnels, and scars. It often affects areas where skin meets skin and tends to return over time. The pattern and impact can differ widely from one person to another.
In the HS context
Throughout this site, HS means this condition rather than a general sweat-gland problem.
How it may be described
- Common locations include the armpits, groin, buttocks, inner thighs, and breast folds.
What to record for an appointment
- Which locations recur and how has the pattern changed over time?
Do not automatically confuse with
Boils in skin folds. One bump does not establish the cause of a recurring skin pattern. ↗
When to seek care. Recurring deep lumps, drainage, tunnels, or scars in skin folds are worth discussing with a dermatologist.I use HS as shorthand for the condition, but my experience does not define anyone else's.
Sources: National Institute of Arthritis and Musculoskeletal and Skin Diseases · American Academy of Dermatology · Checked August 9, 2026 - 02
Suppurativa is the word in the disease name that points to the possible production or release of pus. Not every hidradenitis suppurativa lesion drains, and discharge alone does not identify HS. The word describes one possible feature rather than a requirement for every episode.
In the HS context
It explains part of the name without defining the complete disease pattern.
How it may be described
- A lesion may stay closed, open and drain, or leave a scar after it settles.
What to record for an appointment
- Did the area drain and what did the fluid look like?
- 03
Acne inversa is an older or alternate name for hidradenitis suppurativa that still appears in research and clinical materials. It does not mean ordinary acne located in a fold. In this glossary it names the same chronic inflammatory condition and not a separate subtype.
In the HS context
The term is included so older articles and alternate labels are easier to follow.
How it may be described
- It may appear in publication titles, patient groups, or older records.
What to record for an appointment
- Is acne inversa being used here as another name for HS?
02How HS changes over time 2 entries
- 01
An HS flare is a period when signs or symptoms appear or become more active than a person's usual baseline. It may involve a new lesion, renewed drainage, or increased discomfort. The word describes a change over time and does not prove what caused that change.
In the HS context
The trigger library owns questions about possible contributing factors; this entry only defines flare.
How it may be described
- Flares may affect one familiar site or several areas and can vary in duration.
What to record for an appointment
- What changed from baseline and when did it begin?
Do not automatically confuse with
HS triggers. A flare is an observed period; a trigger is a possible contributor that needs separate evidence. ↗
I use flare for active periods I observe in my own HS, not as proof of one cause.
- 02
Remission is a period when the signs and symptoms of a chronic condition are greatly reduced or not apparent. In hidradenitis suppurativa it does not mean the condition has permanently disappeared. The exact way remission is described can depend on the clinical or personal context.
In the HS context
On this site, Luca uses the word for his own observed experience rather than a promised outcome.
How it may be described
- Its duration and the signs used to describe it can vary.
What to record for an appointment
- Which changes are being used to describe this period?
When I describe my remission, I am reporting my own experience and not predicting anyone else's result.
03Lesions and skin signs 10 entries
- 01
A nodule is a solid, deeper lump in the skin. An abscess is an inflamed cavity containing pus. Both can be painful in hidradenitis suppurativa and can change over time, so surface appearance and touch alone may not reliably separate them.
In the HS context
The distinction supports a clearer symptom history without assigning a label remotely.
How it may be described
- Depth, duration, drainage, recurrence, and location are useful details to record.
What to record for an appointment
- Did the lump open, refill, or recur in the same place?
Do not automatically confuse with
Fold and location guide. The relevant comparisons change by exact body location. ↗
When to seek care. Fever, rapidly spreading redness, severe pain, or quick worsening needs prompt medical attention.Sources: American Academy of Dermatology · MedlinePlus, U.S. National Library of Medicine · Checked August 9, 2026 - 02
A sinus tract in hidradenitis suppurativa is an inflammatory passage beneath the skin, commonly described in patient language as a tunnel. It may connect lesions or surface openings, persist over time, drain repeatedly, and contribute to scarring. Its full extent may not be visible from the surface.
In the HS context
Sinus tract and tunnel refer to a structural feature beyond one closed nodule.
How it may be described
- Clues described in sources include repeated drainage, separate openings, firmness, or a cord-like area under the skin.
- The visible opening may show only part of the tract beneath it.
What to record for an appointment
- How many openings are present and do they drain repeatedly?
- Is there a firm or cord-like area between lesions?
Do not automatically confuse with
Tunneling wound. A wound-care tunnel can occur in other conditions; HS tunnel is anchored to the HS disease context. ↗
When to seek care. Severe pain, fever, spreading redness, or rapid worsening needs prompt medical attention.Sources: American Academy of Dermatology · NCBI Bookshelf, StatPearls · National Institute of Arthritis and Musculoskeletal and Skin Diseases · Checked August 9, 2026 - 03
A draining tunnel is an HS tunnel or sinus tract with an opening that releases fluid, blood, or pus. Drainage may be intermittent and can return through the same site. The phrase describes what the tract is doing at that time, not a separate disease or permanent state.
In the HS context
The dedicated tunnel page owns the full explanation and terminology comparison.
How it may be described
- Clothing or dressings may show recurring wet spots from one familiar opening.
What to record for an appointment
- How often does it drain and does the fluid exit from the same opening?
Do not automatically confuse with
Sinus tracts and tunnels. Draining describes current activity; tunnel describes the underlying passage. ↗
- 04
Exudate is fluid released from inflamed tissue or a wound. It may be clear, blood-tinged, or mixed with pus. In hidradenitis suppurativa, the word describes what drains from a lesion or tunnel. Color and odor alone do not establish its cause or whether bacteria are involved.
In the HS context
It is a neutral description of drainage rather than a conclusion about the lesion.
How it may be described
- Amount, color, odor, frequency, and blood can be recorded over time.
What to record for an appointment
- How often does fluid appear and has its amount or appearance changed?
- 05
Suppuration means the formation or discharge of pus in inflamed tissue. It explains part of the name hidradenitis suppurativa and may occur with abscesses or draining tunnels. It does not mean every HS lesion contains pus, and it does not establish a bacterial infection by itself.
In the HS context
The word names one possible feature rather than the whole HS pattern.
How it may be described
- It may be described when thick material exits an opening or abscess.
What to record for an appointment
- Was the discharge new or recurring and were fever or spreading redness present?
When to seek care. Fever, rapidly spreading redness, or worsening pain needs medical attention.Sources: American Academy of Dermatology · MedlinePlus, U.S. National Library of Medicine · Checked August 9, 2026 - 06
Purulent means containing pus or having a pus-like appearance. In HS materials it may describe drainage from an abscess or tunnel. The word records appearance rather than the complete cause. Purulent fluid does not by itself establish hidradenitis suppurativa or confirm a bacterial infection.
In the HS context
It is a descriptive adjective, not a standalone interpretation of a report or wound.
How it may be described
- The material may be thick and can be mixed with blood or clearer fluid.
What to record for an appointment
- What did the drainage look like and were there whole-body symptoms?
When to seek care. Fever, spreading redness, or rapid worsening needs prompt medical attention.Sources: MedlinePlus, U.S. National Library of Medicine · American Academy of Dermatology · Checked August 9, 2026 - 07
Induration means an area of tissue feels unusually firm or hardened compared with nearby skin. In hidradenitis suppurativa it may be noted around inflammation, scarring, or a tract beneath the surface. The word describes texture and does not explain the cause without clinical context.
In the HS context
Firmness can be recorded alongside pain, drainage, openings, and change over time.
How it may be described
- The area may feel thicker, less flexible, or cord-like under the skin.
What to record for an appointment
- Is the firmness new, changing, painful, or linked to nearby openings?
- 08
A comedone is a hair-follicle opening blocked with keratin and oil, often seen as a dark spot when open. Comedones are common in acne and can also appear in hidradenitis suppurativa. Paired or connected openings carry a more specific label in HS literature.
In the HS context
One ordinary blackhead is nonspecific; a paired pattern is discussed separately.
How it may be described
- It can look like a small flat or slightly raised dark opening.
What to record for an appointment
- Are the openings single, paired, or near scars and recurring lesions?
Do not automatically confuse with
Double and tombstone comedones. A paired opening has a different descriptive role from one common blackhead. ↗
Sources: American Journal of Obstetrics and Gynecology · Canadian Family Physician · Checked August 9, 2026 - 09
Lesions
Double or tombstone comedones
Also called: double-headed comedones · double-ended comedones
In-depth entryDouble comedones are two nearby or connected dark follicular openings, also described as double-headed or double-ended. Tombstone comedones is another HS-associated label for open, scar-related plugs. These terms appear in hidradenitis suppurativa literature but do not replace an in-person skin assessment.
In the HS context
The paired or scar-linked configuration is more HS-specific than one ordinary blackhead.
How it may be described
- They may look like two black dots connected beneath a small bridge of skin.
- They can sit near scarring or an area with earlier nodules and drainage.
What to record for an appointment
- When did the openings appear and has the area had deep or draining lesions?
- Are scars, tunnels, or other paired openings nearby?
Do not automatically confuse with
Single comedone. One blackhead is common and does not carry the same descriptive specificity. ↗
Sources: American Journal of Obstetrics and Gynecology · Canadian Family Physician · American Academy of Dermatology · Checked August 9, 2026 - 10
A hypertrophic scar is a thick, raised scar that stays within the boundary of the original injury. Repeated inflammation from hidradenitis suppurativa can leave several scar patterns and may affect skin movement. Not every raised scar is the same, and hypertrophic names one particular form.
In the HS context
HS scarring may also look bridged, rope-like, contracted, or linked to prior tunnels.
How it may be described
- The scar can feel firm and stand above surrounding skin.
What to record for an appointment
- Is the scar changing, painful, or limiting movement?
04Conditions that can look similar 5 entries
- 01
Boil is a common word for an infected hair-follicle lump, while a skin cyst is a sac under the skin that may become inflamed. Warmth, pain, swelling, or discharge can overlap. Neither word is interchangeable with hidradenitis suppurativa, which depends on a broader recurring pattern.
In the HS context
A dedicated comparison page owns this symptom-level question.
How it may be described
- Onset, a central opening, mobility, clustering, and change over time can differ.
What to record for an appointment
- Is this a single event or part of a repeated fold pattern?
Do not automatically confuse with
Boil vs cyst guide. The owner page compares the terms and keeps location-specific safety gates visible. ↗
- 02
Folliculitis is inflammation around one or more hair follicles, often appearing as small bumps or pustules centered on hairs. It can resemble surface features seen around hidradenitis suppurativa, but depth, recurrence, tunnels, drainage, and scarring create a different history to discuss with a clinician.
In the HS context
It is a common comparison for small bumps after shaving, sweat, or friction.
How it may be described
- The bumps may be numerous, superficial, itchy, or centered on visible hairs.
What to record for an appointment
- Are the bumps hair-centered and linked in time to shaving or friction?
Do not automatically confuse with
Boils in folds. The location guide separates a surface episode from a recurring deep pattern. ↗
- 03
Keratosis pilaris is a common condition in which keratin plugs create small rough bumps around hair follicles. It usually looks and feels like many surface dots. It is not the same as the deep nodules, abscesses, drainage, tunnels, or scarring described in hidradenitis suppurativa.
In the HS context
The comparison is most relevant for widespread rough bumps on thighs or buttocks.
How it may be described
- The bumps tend to be small, numerous, and sandpaper-like rather than deep.
What to record for an appointment
- Are the spots rough and widespread or deep, painful, and recurring?
Do not automatically confuse with
Location guide. The fold pages distinguish rough surface patterns from deeper recurring lesions. ↗
- 04
A pilonidal sinus is a small passage or cavity in the skin, usually at the top of the buttock cleft, that can become inflamed or drain. It is not another name for hidradenitis suppurativa, though nearby location, pain, and discharge can create confusion.
In the HS context
Exact location on the buttock cheek or midline cleft changes the clinical path.
How it may be described
- There may be a small opening, swelling, or discharge at the top of the cleft.
What to record for an appointment
- Is the spot on the cheek or directly in the cleft midline?
Do not automatically confuse with
Boils on buttocks. The page separates buttock cheek, upper cleft, and perianal boundaries. ↗
When to seek care. Increasing pain, swelling, bleeding, or pus warrants an in-person medical assessment. - 05
A tunneling wound is a wound with a channel that extends beneath the visible skin opening. The term belongs broadly to wound care and can arise in settings unrelated to hidradenitis suppurativa. An HS tunnel may overlap in everyday wording, but the two phrases are not universal synonyms.
In the HS context
The HS context depends on the broader recurring pattern and not on the word tunneling alone.
How it may be described
- The opening may be smaller than the channel described beneath the skin.
What to record for an appointment
- Which condition and wound type did the clinician mean when using the term?
Do not automatically confuse with
HS sinus tract. The HS page explains tunnels within a specific chronic inflammatory disease. ↗
05Severity and scoring 2 entries
- 01
Hurley staging is a three-level system used to describe structural extent in hidradenitis suppurativa, with attention to abscesses, tunnels, and scarring. It gives a broad clinical snapshot. It does not capture every change in lesion count, pain, drainage, or daily impact.
In the HS context
The dedicated Hurley page explains the levels and their limits without self-staging.
How it may be described
- The stage reflects the pattern and distribution of tunnels and scars.
What to record for an appointment
- Which findings led the clinician to use that stage?
Do not automatically confuse with
Hurley stages. The owner page covers the classification in full. ↗
- 02
IHS4 is a dynamic severity score for hidradenitis suppurativa based on counts of inflammatory nodules, abscesses, and draining tunnels, with different weights for each lesion type. It was developed for clinical and research use. This glossary does not provide a calculator or support self-scoring.
In the HS context
Unlike Hurley staging, IHS4 is designed to change as active lesion counts change.
How it may be described
- A clinician records defined lesion types and interprets the total in context.
What to record for an appointment
- Which lesions were counted and what is the score being used to monitor?
Do not automatically confuse with
Hurley stage. Hurley describes structural extent, while IHS4 tracks weighted active lesion counts. ↗
06HS medications 3 entries
- 01
A topical antibiotic is a medicine applied to the skin rather than swallowed or delivered another way. Certain products may be part of a clinician-directed hidradenitis suppurativa plan. The term only identifies how a medicine is applied and does not specify which product fits an individual.
In the HS context
Product choice and use depend on a person's clinical situation and prescriber guidance.
How it may be described
- Topical products may come as a gel, lotion, or solution.
What to record for an appointment
- What is this product intended to address in the wider plan?
- 02
A biologic drug is produced using living systems and targets a specific part of immune or inflammatory activity. Some biologics are approved for selected people with hidradenitis suppurativa. Eligibility, expected benefit, risks, monitoring, and product choice require an individualized specialist discussion.
In the HS context
Biologic names a medicine class, not one interchangeable product or automatic next step.
How it may be described
- A record may use a generic name, brand name, or biosimilar name.
What to record for an appointment
- What is the treatment goal and which monitoring applies to my situation?
Sources: American Academy of Dermatology · National Institute of Arthritis and Musculoskeletal and Skin Diseases · Checked August 9, 2026 - 03
Adalimumab is a biologic medicine that blocks TNF, a protein involved in inflammatory signaling. It is used across several conditions and is among the authorized options for some people with hidradenitis suppurativa. Selection, monitoring, and administration belong in a specialist-led plan.
In the HS context
The generic name identifies one active ingredient rather than a choice based on the HS label alone.
How it may be described
- It may appear under a brand name or the name of a biosimilar.
What to record for an appointment
- Why is this option being discussed for my situation and what monitoring is involved?
07Procedures 2 entries
- 01
Incision and drainage is a clinician-performed procedure that opens an abscess so its contents can leave. In hidradenitis suppurativa it may relieve a selected acute collection but may not remove a persistent tunnel or the tissue involved over time. It is not a do-it-yourself procedure.
In the HS context
It differs from procedures intended to address a selected persistent tunnel or recurring lesion.
How it may be described
- The phrase may appear in emergency, office, or surgical records.
What to record for an appointment
- What is the goal of the procedure and what underlying structure may remain?
When to seek care. Do not cut, puncture, or squeeze an abscess at home; seek professional assessment.Sources: American Academy of Dermatology · MedlinePlus, U.S. National Library of Medicine · Checked August 9, 2026 - 02
Deroofing is a specialist procedure that opens the top of a selected hidradenitis suppurativa tunnel or persistent lesion while preserving surrounding tissue where possible. It is different from simply draining an abscess. Patient selection, technique, wound care, risks, and follow-up require professional oversight.
In the HS context
This entry stays brief until a relevant dermatologist review is available.
How it may be described
- The term may arise when discussing localized tunnels or lesions that repeatedly return.
What to record for an appointment
- Why is the procedure being considered and which structure would it address?
Do not automatically confuse with
Incision and drainage. Drainage empties a collection, while deroofing addresses a selected persistent structure. ↗
No entries match your search. Try a synonym or a broader term.
Sources
- Hidradenitis suppurativa: Signs and symptomsAmerican Academy of Dermatology · institutionalClinicalGuidance
- Hidradenitis Suppurativa (HS)National Institute of Arthritis and Musculoskeletal and Skin Diseases · institutionalClinicalGuidance
- Hidradenitis SuppurativaNCBI Bookshelf, StatPearls · peerReviewedPublication
- Hidradenitis suppurativaNHS · institutionalClinicalGuidance
- Diagnosis and management of hidradenitis suppurativa in womenAmerican Journal of Obstetrics and Gynecology · peerReviewedPublication
- What is hidradenitis suppurativa?Canadian Family Physician · peerReviewedPublication
- Hidradenitis suppurativa: Diagnosis and treatmentAmerican Academy of Dermatology · institutionalClinicalGuidance
- Development and validation of the International Hidradenitis Suppurativa Severity Score System (IHS4)British Journal of Dermatology · peerReviewedPublication
- Folliculitis: Symptoms and causesMayo Clinic · institutionalClinicalGuidance
- Epidermoid cysts: Symptoms and causesMayo Clinic · institutionalClinicalGuidance
- Pilonidal sinusNHS · institutionalClinicalGuidance
- Keratosis pilaris: an update and approach to managementMinerva Medica · peerReviewedPublication
- Skin abscessMedlinePlus, U.S. National Library of Medicine · institutionalClinicalGuidance
Patient-written, checked against the listed sources, and not medically reviewed. Educational information, not personal clinical interpretation.