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PubMed This is a summary of 24 peer-reviewed journal articles Updated
Dermatology

Identifying the Triad: Symptoms and Warning Signs

At a Glance

PASH syndrome involves severe acne, hidradenitis suppurativa, and pyoderma gangrenosum, which may appear at different times. Minor skin trauma can worsen ulcers; spreading redness, fever, confusion, crackling under the skin, or unusual pain need urgent assessment.

Living with PASH syndrome means managing a “triad” of skin conditions that often overlap. While each part of the triad—Pyoderma Gangrenosum (PG), Acne, and Hidradenitis Suppurativa (HS)—has its own set of symptoms, they are all driven by the same underlying overactive immune response [1][2].

The Clinical Triad

The way PASH appears can vary, but most patients experience a combination of the following:

  • Severe Acne: This is often the first sign, frequently starting in adolescence [2]. It is usually more than just a few pimples; it often presents as severe nodulocystic acne or acne conglobata, which involve deep, painful, interconnected cysts and nodules that can leave significant scarring [3][1].
  • Hidradenitis Suppurativa (HS): This usually appears after acne. It causes recurrent, boil-like lumps (nodules) and abscesses in areas where skin rubs together, such as the armpits, under the breasts, and the groin [4][5]. Over time, these can form “sinus tracts”—tunnels under the skin that drain fluid—and lead to thick, rope-like scars [6][7].
  • Pyoderma Gangrenosum (PG): Often the last of the three to appear, PG is the most aggressive part of the triad [5]. It begins as small bumps or blisters that rapidly transform into large, extremely painful ulcers [8]. These ulcers typically have a “violaceous” (purplish) border that looks “undermined,” meaning the edge of the ulcer hangs over the wound bed [9][10].

Understanding Pathergy: The Trauma Trigger

A unique and frustrating feature of PASH (specifically the PG component) is pathergy. This is a phenomenon where minor trauma to the skin triggers the immune system to create a new ulcer or cause an existing one to expand rapidly [11][12].

Pathergy is why seemingly helpful medical procedures can sometimes backfire. Common triggers include:

  • Surgical incisions or “lancing” (incision and drainage) of an abscess [13][5].
  • Aggressive “debridement” (cleaning out dead tissue from a wound) [10][14].
  • Needle sticks or biopsies [12].
  • Minor scrapes or even the removal of strong adhesive bandages [15][16].

Because of pathergy, your doctors must be very cautious. If you need elective surgery, your care team should ideally coordinate with a dermatologist to ensure your inflammation is well-controlled with medication before any procedure begins [17][18].

Is It a Flare or an Infection?

Because PG ulcers and HS abscesses look like infections, many patients are mistakenly treated with multiple rounds of standard antibiotics that don’t work [10][13]. PASH is primarily autoinflammatory, meaning the fluid you see is often made of white blood cells (neutrophils) reacting to dysregulated inflammatory signaling rather than primarily bacteria [19][20].

However, because these are open wounds, a secondary bacterial infection can happen at the same time [21]. Distinguishing between the two is critical for your safety, and it is not something you should try to do on your own at home.

When to Call Your Doctor Promptly

Contact your dermatology team promptly for an urgent evaluation if you notice:

  • An existing ulcer is rapidly getting larger.
  • You develop new severe pain.
  • New HS nodules are forming rapidly.
  • You have increased drainage that is suddenly changing in volume or character.

Red Flags: When to Seek Emergency Care

You should go to an emergency department or urgent care immediately if you experience signs of a serious, spreading infection:

  • Rapidly Spreading Redness: If the redness around an ulcer is spreading quickly [22].
  • Systemic Symptoms: Fever, chills, extreme fatigue, or confusion [19].
  • “Out of Proportion” Pain: Pain that is suddenly much worse than your usual flare pain, especially if the skin feels very tender far beyond the ulcer itself [13][22].
  • Crepitus: A “crackling” or “crunchy” feeling under the skin when you press near the wound (this can indicate gas-producing, life-threatening bacteria) [22].
  • Red Streaks: Red lines moving away from the wound toward your heart.

Disease Progression

While many patients follow a pattern—starting with severe acne in their teens, followed by HS, and then PG in their 20s or 30s—this is not a strict rule [2][5]. Some people may have all three symptoms appear at once, or others may exhibit a PASH-like phenotype with only two features, though a true PASH diagnosis requires all three [23][24]. The severity of each component can also “cycle,” meaning your acne might be quiet while your HS is flaring. Tracking these changes can help your doctor adjust your treatments to target the most active part of the disease [2].

Common questions in this guide

What are the three conditions in PASH syndrome?
PASH stands for pyoderma gangrenosum, acne, and hidradenitis suppurativa. The acne is often severe and nodular, hidradenitis suppurativa causes recurrent nodules or abscesses in skin folds, and pyoderma gangrenosum causes painful ulcers. A true PASH diagnosis requires all three features, although they may not begin at the same time.
Can PASH symptoms start at different times?
Yes. Severe acne often begins in adolescence, hidradenitis suppurativa may appear later, and pyoderma gangrenosum is often the last feature, but this pattern is not fixed. Some people develop the features together, and one part can flare while another is quiet.
What is pathergy, and how can it affect a PASH ulcer?
Pathergy means that a small injury can trigger a new pyoderma gangrenosum ulcer or make an existing ulcer enlarge quickly. Possible triggers include surgery, incision and drainage, cleaning dead tissue from a wound, needle sticks, biopsies, scrapes, and strong adhesive removal. Tell your dermatology team about this risk before a procedure so they can plan safely.
How can I tell whether a PASH flare is infected?
You usually cannot tell reliably at home because sterile inflammation and a secondary bacterial infection can look similar. A clinician may examine the wound and decide whether testing such as a swab or tissue culture is needed; antibiotics are used when bacterial infection is suspected or confirmed, not for every inflammatory flare.
Which PASH warning signs mean I should seek emergency care?
Seek emergency care for rapidly spreading redness, fever or chills, extreme fatigue, confusion, pain that is suddenly much worse or extends beyond the wound, crackling under the skin, or red streaks moving away from the wound. These can indicate a serious spreading infection and should not be managed at home.
What should I do before a biopsy or surgery if I have PASH?
Tell the clinician performing the procedure that you have PASH and discuss the risk of pathergy with your dermatology team. For elective procedures, the care team may first aim to control inflammation with medication and plan a wound approach that minimizes unnecessary skin trauma.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Given that I have PASH, how can we differentiate between a sterile flare and a secondary infection in my ulcers?
  2. 2.Is my current acne classified as nodulocystic or conglobata, and how does that affect my treatment plan?
  3. 3.Are there specific steps we should take to protect my skin from pathergy if I need a biopsy or surgery in the future?
  4. 4.What are the specific 'red flag' symptoms for me personally that should trigger an immediate call to your office versus a visit to the ER?
  5. 5.If we suspect an infection, will you perform a tissue culture or a swab, and how will those results be interpreted alongside my PG?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (24)
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    Pyoderma Gangrenosum, Acne, and Hidradenitis Suppurativa Syndrome: A Case Report and Literature Review.

    Huang J, Tsang LS, Shi W, Li J

    Frontiers in medicine 2022; (9()):856786 doi:10.3389/fmed.2022.856786.

    PMID: 35402426
  2. 2

    A complex case of PASH syndrome: pyoderma gangrenosum, acne, suppurative hidradenitis, and Crohn's disease in a 36-year-old smoker.

    Abdul Rahman N, Jazmati A, Roumi Jamal B, et al.

    Annals of medicine and surgery (2012) 2024; (86(10)):6280-6284 doi:10.1097/MS9.0000000000002533.

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    A Unified Concept of Acne in the PAPA Spectrum Disorders.

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    Concurrent Hidradenitis Suppurativa and Pyoderma Gangrenosum in a Pediatric Cohort: A Retrospective Case Series.

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    PsAPASH: a rare and recent autoinflammatory syndrome associated with hidradenitis suppurativa.

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    Neutrophilic dermatosis and hidradenitis suppurativa in patients with Behçet's disease: A neutrophilic disease in the spectrum of autoinflammatory syndromes.

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    Resolution of Pyoderma Gangrenosum During Adjuvant Breast Cancer Therapy.

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This page explains how PASH symptoms, pathergy, and infection warning signs can appear for educational purposes; it does not replace medical advice. Your dermatology team should assess your wounds and tell you when to seek urgent or emergency care.

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