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PubMed This is a summary of 19 peer-reviewed journal articles Updated
Urology · Interstitial Cystitis/Bladder Pain Syndrome

Pathology & Subtypes: Hunner Lesions and Beyond

At a Glance

Interstitial cystitis/bladder pain syndrome has different subtypes. Cystoscopy can identify Hunner lesions, while biopsy mainly helps rule out bladder cancer and other inflammatory conditions; the ESSIC system uses numbers for cystoscopy findings and letters for biopsy findings to guide care.

If you have been diagnosed with Interstitial Cystitis or Bladder Pain Syndrome (IC/BPS), it is important to know that this is not a single disease. Instead, it is a collection of different “subtypes” that may look the same on the surface but have different biological causes [1][2].

Doctors selectively use a specialized exam called a cystoscopy (a small camera inserted into the bladder) and sometimes a biopsy (taking a tiny tissue sample) to determine which subtype you have. The most significant dividing line is the presence or absence of a Hunner lesion [3][4].

What is a Hunner Lesion?

A Hunner lesion is not actually a typical “ulcer,” though it is sometimes called one. It is a distinct, reddened area on the bladder wall where the blood vessels look like they are radiating out from a central scar [5][6].

During a procedure called hydrodistension—where the bladder is gently stretched with fluid while you are under anesthesia—these lesions may crack or split, creating a “waterfall” pattern of bleeding [5][7]. While they are very painful, finding them is actually helpful because it gives your doctor a clear target for treatment [8].

The Two Main Subtypes

Research has identified two primary ways IC/BPS presents in patients:

  • Hunner-Type (Inflammatory/Bladder-Centric): This type is characterized by severe inflammation. The bladder’s protective lining, the urothelium, is often “denuded,” meaning it is literally falling off or missing in patches [1][9]. Patients with this type tend to be older, have much smaller bladder capacities, and experience high levels of frequency and nocturia (waking up at night to go) [10].
  • Non-Hunner Type (Centralized/Neurological): This type is highly variable. The bladder lining often looks normal or shows only glomerulations (nonspecific pinpoint bleeds that can happen after stretching the bladder) [11][2]. A normal bladder does not establish that the bladder is not the primary source of symptoms. However, for many in this group, the pain may involve the nerves, the brain, or pelvic floor dysfunction and other conditions like fibromyalgia or IBS [4][10].

Reading Your Pathology Report

If your doctor took a biopsy, the pathology report will describe what the tissue looks like under a microscope. This is done primarily to rule out other conditions that can mimic IC/BPS:

  • Carcinoma in Situ (CIS): A type of high-grade bladder cancer that can look exactly like a red, inflamed patch of cystitis [12].
  • Eosinophilic Cystitis: A rare condition where a specific type of white blood cell (eosinophil) invades the bladder wall, often due to an allergy or autoimmune trigger [13].
  • Mast Cells: You may see “mast cells” mentioned. While these are common in IC/BPS, they are also found in many other conditions, so their presence alone isn’t enough to confirm a diagnosis [1][13].

The ESSIC Classification System

The ESSIC (International Society for the Study of BPS) uses an optional descriptive grid to classify your disease based on what the doctor saw (Cystoscopy) and what the lab found (Biopsy) [2][14].

  • Numbers (1, 2, or 3) describe the cystoscopy. A “3” means Hunner lesions were found [15].
  • Letters (A, B, or C) describe the biopsy. A “C” means the lab found classic signs of inflammation or damage [14].

A classification of 3C is the “classic” inflammatory Hunner-type IC, while a 1A or 2A usually points toward a non-Hunner pain syndrome [15][16].

Tests That May Be Considered (If Clinically Indicated)

To ensure your diagnosis is accurate, these tests may be part of your evaluation, but are not required for every IC/BPS diagnosis:

  • [ ] Urine Culture: Helps assess infection, though a negative culture does not absolutely prove bacteria are absent (especially after antibiotics) [17].
  • [ ] Post-Void Residual (PVR): To ensure your bladder is emptying fully [18].
  • [ ] Pelvic Floor Exam: A physical check of the muscles for tenderness or trigger points [19].
  • [ ] Cystoscopy Report: Detailing if Hunner lesions were present, their location, and if any “waterfall” bleeding occurred [6].
  • [ ] Bladder Capacity: The maximum amount of fluid your bladder could hold under anesthesia (if hydrodistension was performed) [7].
  • [ ] Biopsy Results: Specifically ruling out cancer or other rare inflammatory diseases [13][12].

Common questions in this guide

What does a Hunner lesion mean in interstitial cystitis?
A Hunner lesion is a distinct red, inflamed area on the bladder wall with blood vessels that radiate from a central scar. It is sometimes called an ulcer, but it is not a typical ulcer. During bladder stretching under anesthesia, it may split and bleed in a waterfall pattern, giving the doctor a specific area to treat.
What is the difference between Hunner-type and non-Hunner IC/BPS?
Hunner-type disease is associated with severe inflammation, patches where the bladder lining is missing, smaller bladder capacity, and frequent or nighttime urination. Non-Hunner disease may have a normal-looking bladder or nonspecific pinpoint bleeding after stretching. In some people, pain may also involve nerves, the brain, pelvic floor dysfunction, or conditions such as fibromyalgia or IBS.
Can a normal cystoscopy rule out interstitial cystitis?
No. Some people with non-Hunner IC/BPS have a normal-appearing bladder, and glomerulations are nonspecific and can occur after stretching. Cystoscopy findings must be interpreted with symptoms and other evaluation; a normal bladder appearance does not by itself prove that the bladder is not the source of pain.
What does a 3C ESSIC classification mean?
ESSIC numbers describe what was seen during cystoscopy, while letters describe biopsy findings. A 3 means Hunner lesions were found, and C indicates classic signs of inflammation or tissue damage. Together, 3C usually describes the classic inflammatory Hunner-type form of IC/BPS.
What can a biopsy show in an IC/BPS evaluation?
A biopsy is used mainly to rule out conditions that can look like inflamed IC/BPS, including carcinoma in situ, a high-grade bladder cancer, and eosinophilic cystitis. It may also mention mast cells, but mast cells can occur in other conditions and do not confirm IC/BPS by themselves. Your pathologist and urologist should interpret the result in context.
What tests might be included when doctors assess IC/BPS subtypes?
Depending on your symptoms and clinical situation, evaluation may include a urine culture, measurement of urine left after urination, a pelvic floor exam, cystoscopy, bladder capacity during hydrodistension, or biopsy. These tests are not required for every IC/BPS diagnosis. They help assess infection, emptying, muscle tenderness, bladder findings, and conditions that can mimic the syndrome.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Does my cystoscopy report show 'Hunner lesions' or just 'glomerulations'? How does this change my treatment plan?
  2. 2.What was my 'maximal bladder capacity' under anesthesia? Is this considered low or within a normal range?
  3. 3.Did the biopsy show signs of 'urothelial denudation' or plasma cells? What do these markers tell us about the cause of my pain?
  4. 4.Based on the ESSIC classification, where does my bladder fall? (e.g., 2A, 3C)?
  5. 5.Are we certain we have ruled out carcinoma in situ (CIS) or other inflammatory conditions like eosinophilic cystitis?
  6. 6.If I have Hunner lesions, what is the likelihood they will need to be treated with cauterization or laser therapy?

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 (19)
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    Genomics and Histopathology in Interstitial Cystitis/Bladder Pain Syndrome.

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    Clinical guidelines for interstitial cystitis/bladder pain syndrome.

    Homma Y, Akiyama Y, Tomoe H, et al.

    International journal of urology : official journal of the Japanese Urological Association 2020; (27(7)):578-589 doi:10.1111/iju.14234.

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    Optimizing the Diagnosis of Interstitial Cystitis/Bladder Pain Syndrome: An ESSIC Proposal.

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    Clinical Implications of Glomerulation After Cystoscopic Hydrodistention in Patients With Interstitial Cystitis and Bladder Pain Syndrome.

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    Long-Term Clinical Outcomes of Transurethral Resection of Hunner Lesions Combined With Bladder Hydrodistension for Patients With Interstitial Cystitis at a Tertiary Referral Center in Japan.

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This page explains IC/BPS cystoscopy and biopsy findings for informational purposes only and does not constitute medical advice. Your urologist and pathologist should interpret your report and discuss treatment with you.

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