Acne Inversa vs. Pilonidal Sinus: What Should You Distinguish?

Written by Dr. rer. nat. Dennis Alexander Kwiatkowski

When Symptoms “on the Backside” Are Not Clear-Cut

Pain, discharge, or an abscess on the buttocks is often quickly filed away under a single umbrella term in everyday life. For a medical classification, however, it makes a difference whether mainly the tailbone and gluteal cleft region is affected or whether a broader recurring HS pattern is present.

What Is More Consistent with a Pilonidal Sinus

A pilonidal sinus, often also referred to as a tailbone fistula, typically affects the region of the gluteal cleft near the tailbone. It can remain symptom-free, develop an acute abscess, or chronically discharge secretion.

If symptoms repeatedly occur in exactly this region, a pilonidal sinus definitely belongs in a medical evaluation.

What Is More Suggestive of Acne Inversa

HS can occur on the buttocks, perianally, or perineally. The suspicion grows stronger when other typical HS features are also present:

• recurring deep nodules or abscesses,
• additional affected regions such as the armpits, groin, or skin folds under the breasts,
• scars, indurations, or tunnels (sinus tracts) following repeated inflammation,
• a course that is not limited to a single spot in the gluteal cleft.

Overlaps are also possible. For this reason, “either/or” is not always the best initial assumption.

Why the Exact Location Helps

For the consultation, “on the backside” is often too imprecise. It is more helpful to consider:

1. Is the spot in the central gluteal cleft near the tailbone?
2. Is it more toward the side of the buttocks, perianal, perineal, or in several regions?
3. Are there similar lesions in the armpits, groin, or under the breasts?
4. Do openings, scars, or recurring weeping areas remain?

These questions do not replace an examination. They make the findings more precise for the examination.

Who Should Classify This?

Recurring symptoms in the tailbone region may require surgical or coloproctological evaluation. If an HS pattern is also possible at the same time, dermatological classification is important. In the case of severe pain, fever, or rapidly increasing inflammation, the area should be medically assessed promptly.