What is Hunner's lesion?

What is Hunner's Lesion?

Hunner's lesion is a specific inflammatory bladder finding seen on cystoscopy that represents the only consistent cystoscopic feature diagnostic of interstitial cystitis/bladder pain syndrome (IC/BPS), characterized by a reddened mucosal area with small vessels radiating toward a central scar that splits during bladder distention, often with a waterfall bleeding pattern. 1

Cystoscopic Appearance

Hunner's lesions present with considerable variation in their visual appearance, but share common features:

• Classic presentation: A reddened mucosal area with small vessels radiating towards a central scar, which splits at bladder distention and typically shows a waterfall bleeding pattern 2
• Variations include: Classic lesions with or without a central coagulum, inflamed lesions, non-inflamed lesions, groupings of lesions, and lesions with red waterfall bleeding appearance 3
• Identification technique: The lesion is identified as an area of erythema that reproduces the patient's pain when touched by the cystoscope 4
• Enhanced visualization: Mild bladder distention makes Hunner lesions easier to identify when cracking and mucosal bleeding become evident 1, 5

Histopathological Features

The microscopic findings distinguish Hunner lesions from other bladder conditions:

• Characteristic findings: Inflammatory infiltrates, granulation tissue, detrusor mastocytosis, fibrin deposits, subepithelial chronic inflammatory changes, and epithelial denudation 6, 2
• Diagnostic confirmation: Histopathology is the definitive method to confirm Hunner lesion disease 7

Clinical Significance and Phenotyping

Hunner lesion disease represents a distinct clinical phenotype that should be separated from other forms of bladder pain syndrome due to fundamental differences in presentation, pathology, and treatment response. 6, 7

Distinguishing Characteristics:

• Age: Older onset age compared to non-Hunner lesion IC/BPS 6, 2
• Symptoms: Severe bladder-centric symptoms 6
• Bladder capacity: Reduced anatomic bladder capacity 6, 2
• Treatment response: Favorable and dramatic response to lesion-targeted therapies 6
• Prevalence: Reported between 5-57% of IC/BPS patients, with higher frequency in older patients 2

Diagnostic Approach

Cystoscopy remains the only reliable way to diagnose the presence of Hunner lesions and should be performed in patients for whom these lesions are suspected. 1

Key Diagnostic Points:

• Office cystoscopy: Most Hunner lesions can be identified during office visits using flexible cystoscopy with local anesthesia without requiring hydrodistention or general anesthesia 3
• Standard technique: Cystoscopy with hydrodistention and redistention of the bladder is considered the standard approach for comprehensive evaluation 2
• Early diagnosis: Early diagnosis by cystoscopy is recommended in patients suspected to have these lesions, without requiring them to fail other behavioral or medical treatments first 1
• Not routine: Performing cystoscopy for every IC/BPS patient is not advisable since younger patients have a much lower prevalence of Hunner lesions, making the benefits/risks ratio unfavorable 1

Treatment Implications

If Hunner lesions are present, fulguration with electrocautery and/or injection of triamcinolone should be performed, as this represents one of the few IC/BPS therapies resulting in improvement measured in months with only a single exposure. 1

Treatment Outcomes:

• Symptom improvement: Most patients with Hunner lesions will respond to treatment, with reported improvement rates of 76% mean improvement and 100% improvement in some patients 1, 4
• Durability: Hunner lesion treatment results in improvement measured in months following a single procedure 1
• Recurrence management: Symptoms can recur and periodic retreatment is likely necessary, but repeat ablation offers symptomatic improvement 1, 4

Common Pitfalls

• Misidentification: Glomerulations (pinpoint petechial hemorrhages) are commonly confused with Hunner lesions but are non-specific findings that can occur in asymptomatic patients and other conditions 1
• Inadequate visualization: Failure to perform adequate bladder distention may result in missed Hunner lesions 5
• Delayed diagnosis: Requiring patients to fail multiple treatments before performing cystoscopy delays definitive diagnosis and effective treatment in patients who would respond dramatically to lesion-directed therapy 1