Can atypical anal fissures be benign?

Can Atypical Anal Fissures Be Benign?

Yes, atypical anal fissures can be benign, but they require investigation to rule out serious underlying pathology before assuming a benign etiology. While most atypical fissures warrant concern for conditions like inflammatory bowel disease, sexually transmitted infections, or malignancy, not all atypical presentations indicate serious disease 1, 2.

Understanding Atypical Fissure Characteristics

Atypical fissures are defined by their location or multiplicity:

• Lateral positioning (off the midline) or multiple fissures are considered atypical, as 90% of benign fissures occur in the posterior midline 1, 2
• Anterior fissures occur in 10% of women versus 1% of men and are generally still considered within the typical spectrum 1, 2
• The atypical location itself doesn't confirm malignancy—it simply raises suspicion 2, 3

Conditions Associated with Atypical Fissures

When encountering atypical fissures, the following serious conditions must be excluded:

• Inflammatory bowel disease (Crohn's disease or ulcerative colitis) 1, 2
• Sexually transmitted infections including HIV, syphilis, or herpes 1, 2
• Anorectal cancer 1, 2
• Tuberculosis 1, 2
• Leukemia or other infectious causes 2

However, the presence of an atypical location does not automatically mean one of these conditions is present—it simply mandates investigation 3.

Recommended Diagnostic Approach

The WSES-AAST guidelines provide a clear algorithmic approach for atypical fissures:

1. Collect focused medical history looking specifically for:

   • Symptoms of IBD (diarrhea, weight loss, extraintestinal manifestations)
   • Risk factors for STIs
   • Constitutional symptoms suggesting malignancy or tuberculosis 1

2. Perform complete physical examination with attention to:

   • Fissure location (lateral or multiple)
   • Signs of chronicity (sentinel tags, hypertrophied papillae, visible sphincter muscle)
   • Perianal skin changes suggesting Crohn's disease 1, 2

3. Order laboratory tests based on suspected illness rather than routine testing 1

4. Perform imaging/endoscopy only when specific conditions are suspected:

   • Endoscopy for suspected IBD or colorectal cancer
   • CT scan or MRI for occult perianal sepsis
   • Endoanal ultrasound for complex fistulizing disease 1

Clinical Decision-Making

The key distinction is between primary (benign) and secondary (pathologic) fissures:

• Primary fissures are benign, even if anteriorly located, and respond to conservative management 3
• Secondary fissures (lateral or multiple) indicate underlying pathology and require investigation before treatment 3
• The guideline recommendation is weak (2C evidence), reflecting that not every atypical fissure harbors serious disease, but the consequences of missing malignancy or IBD are severe 1

Common Pitfalls to Avoid

Do not assume all atypical fissures are malignant or inflammatory:

• Some patients may have benign lateral fissures without underlying disease 3
• However, the burden of proof is on excluding serious pathology before proceeding with standard fissure treatment 1, 2

Do not perform extensive workup on typical posterior midline fissures:

• Imaging and endoscopy are not recommended for typical fissures 1
• This avoids unnecessary procedures and healthcare costs 1

Do not delay investigation when red flags are present:

• Failure to heal with 8 weeks of conservative management warrants investigation even for typical-appearing fissures 1
• Constitutional symptoms, significant bleeding, or palpable masses mandate immediate workup 1, 2

Treatment Implications

If investigation excludes serious pathology, atypical but benign fissures can be treated conservatively:

• First-line treatment includes dietary fiber, increased water intake, and sitz baths 1
• Topical calcium channel blockers (diltiazem or nifedipine) or nitrates can be added 1
• Surgical sphincterotomy is reserved for chronic fissures unresponsive to 8 weeks of medical management 1

Multidisciplinary management is essential when secondary causes are identified:

• IBD-related fissures require gastroenterology involvement 3
• Malignancy requires oncologic consultation 3
• STI-related fissures need infectious disease management 2