This is what a pilonidal sinus can look like

Pilonidal Sinus: Classification and pictures

80+ clinical images

On this page about the pilonidal sinus, also known as Pilonidal Sinus , you will find an extensive collection of images to help you better understand your own health problem.

The images on this page are intended to provide you with a visual guide so that you can recognize the characteristic features of Pilonidal Sinus in yourself. Navigate through our picture gallery and find out more about the clinical picture of Pilonidal Sinus. The spectrum ranges from barely visible, dilated hair roots (pits) to finger-thick, cartilage-like hardened fistula ducts.

The images shown on this website may be perceived as distressing or disturbing. We would like to point out that the visual representations of medical conditions are authentic and detailed in order to provide accurate information. The images shown are intended to promote understanding of the diagnosis of pilonidal sinus. However, we would like to point out that the images may not be suitable for everyone and may be perceived as uncomfortable. We recommend viewing the images with caution and seeking medical advice if necessary. These visual representations are not a substitute for individual medical diagnosis or treatment.

The decision to view the images is at the user's own discretion. We accept no responsibility for any inconvenience or distress that may be caused by viewing these images.

Our Munich - Classification

Our Pilonidal Sinus images are arranged according to this classification. It describes frequent constellations of findings in coccygeal fistulas and thus facilitates the decision for the best therapy.

A generally accepted classification does not yet exist. I have therefore listed two other known classifications here, but they fit less to our treatment concept.

Type Description Recommended therapy
Type I A Small fistula with up to max. 3 pits and length 2 cm Sinusectomy
Type I B Simple fistula with a maximum of 3 pits and length over 2 cm Sinusectomy. Possible SiLaC with long, narrow fistula.
Type II A 4 and more pits, any length extension Sinusectomy. Possible SiLaC. Possibly pure pit picking in very young patients.
Type II B Long fistula with a club shaped extension and often a blind end far above the gluteal fold. Sinusectomy. Possibly Karydaki's operation with very extensive findings.
type III Secondary fistula after congenital "sacral pit Sinusectomy.
Type IV A recurrent tubular fistula Sinusectomy. Possibly Karydakis surgery. Laser epilation!
Type IV B recurrent trough fistula Debridement. Sinusectomy. Possibly Karydakis surgery. Laser epilation!

Tezel - Classification

This classification was proposed in 2007 by Ekmel Tezel, professor at Gazi University Ankara:

Type Description Recommended therapy
Type I Pits in the area of the gluteal fold. No symptoms, no history of abscess or secretion Hygiene, shaving, no surgery
type II acute coccyx abscess Abscess splitting via lateral incision. Further surgical therapy after the inflammation has subsided.
type III Pits in the central area of the gluteal fold, history of abscess or secretion "Bascom procedure" - pit picking?
type IV Extended fistula findings with openings also laterally or above the gluteal fold "Bascom procedure" - cleft lift?
Type V Any kind of relapse - recurrence "Bascom procedure" - cleft lift?

Berlin - Classification

This very detailed classification was developed at a consensus conference of surgeons in Berlin:

TYp Description Subtype Description
Type I Solitary pit / fistula opening / wound in the midline, no previous operation, above the tip of the coccyx Type IA Pit / Fistula opening
Type I B Elongated wound
type II Multiple pits / fistula openings / wounds in the midline, no previous surgery, above the tip of the coccyx Type II A 2 - 3 openings
Type II B 4 and more openings
Type III Pits / fistula openings / wounds in the midline and laterally, no previous surgery, above the tip of the coccyx Type III A openings on one side, inside the fold of the buttocks
Type III B openings laterally on both sides, inside the seat fold
Type III C Abscess scar inside the gluteal fold
Type III D Extension to the side or upwards outside the gluteal fold
type IV Primary fistula with extension below the tip of the coccyx, no definite previous operation Type IV A Pits / fistula opening / wound in the midline
Type IV B Extension to the side
Type V Any defect after definitive surgery that persists for more than 3 months. Type V A Unhealed wound, above the tip of the coccyx
Type V B Fistula recurrence, above the tip of the coccyx
Type V C Unhealed wound, below the tip of the coccyx
Type V D Fistula recurrence, below the tip of the coccyx
Clinical classifications of the Pilonidal Sinus
Type II according to Tezel

Coccyx abscess (pilonidal abscess)

Sinus pilonidalis images, acute stage

When an unbearable pain develops overnight: The Pilonidal Sinus usually exists for a long time before it becomes conspicuous by an abscess. The trigger for an abscess is often prolonged sitting or mechanical stress

  • on a long-haul flight
  • after long car journeys
  • in preparation for an examination
  • Workout like situps or bench press

Sometimes even the doctor doesn't see much at first glance. With these alarm signs abscess is very likely:

  • Increasing pain
  • visible bump
  • palpable induration
  • Redness
  • Asymmetry of the gluteal fold
  • Strikingly smooth skin
  • If the abscess has ruptured, pus is discharged

Clinical picture

Sonographic image (ultrasound)

Pilonidal abscess2 Ultrasound image
Small, spherical pilonidal abscess
6 cm abscess ultrasound image
6 cm abscess in the ultrasound image

Pilonidal abscess: treatment

According to the current guideline 2020, immediate removal of the fistula should not be attempted in the acute situation. Due to the accompanying inflammatory reaction of the surrounding area, too much tissue would always be removed. In addition, it is easy to overlook individual pits in the case of severe swelling. 

Ultrasound and palpation findings of a "soft dent in the area of the bump" help to find a favorable location for the Opening the abscess to find.

A small incision provides relief, the pus drains away. The pain quickly subsides.

If the findings are less pronounced, antibiotic treatment may be sufficient in individual cases.

Type I, III and IV according to Tezel

Pilonidal Sinus, primary

Chronic form of pilonidal sinus, not yet operated on

With the types I - III of our classification no operation has taken place yet. In its classification, Tezel differentiates between Type I, corresponding to the "blind fistula" with visible openings without symptoms, and Type III with symptoms.

Type I A: Short fistula ≤ 2 cm and maximum 3 primary openings (pits)

The small, uncomplicated Pilonidal Sinus

Scheme Type I a Fistula
Schematic drawing Pilonidal Sinus Type I A

The small fistula under 2 cm length and with a maximum of 3 pits is sometimes not to be found at first sight.

If the painful point is known, the diagnosis can usually be made with certainty using ultrasound.

First choice treatment: Sinusectomy

Complete, economical triggering with the radio frequency scalpel or the blue 470 nm laser

Alternative: Classic Pit Picking

Pit picking and cleaning of the fistula cavity from hair and skin scales (debridement)

Type I B: Long fistula > 2 cm and and maximum 3 primary openings (pits)

The long, simple Pilonidal Sinus

Pilonidal Sinus pictures: Scheme Type I B Fistula
Schematic drawing Pilonidal Sinus Type I B

We see this type of fistula most frequently in our practice.

An expansion of 10 cm and longer is possible. Causal pits are often far down in the gluteal fold and can only be detected after shaving and viewing with magnifying glasses.

1st choice: sinusectomy

With this type of fistula, the fistula tube can be released through small incisions and the overlying skin can be protected. Result: smaller scars and faster healing

Alternative: Pit Picking and SiLaC

For fistulas longer than 4 - 5 cm, the use of the radially emitting laser probe(SiLaC / FiLaC®) be a gentle alternative to sclerosing the fistula with shorter convalescence and a somewhat lower success rate of 75 - 80 %.

Type II A: Long fistula > 2 cm and and ≥ 4 primary openings (pits).

The long, complex Pilonidal Sinus

Scheme Pilonidal Sinus Type IIB new 2020
Schematic drawing Pilonidal Sinus Type II A

With an average length of 4 - 5 cm, these fistulas also have numerous or closely adjacent pits. This is often the case in patients who have been pre-operated on with Limberg Plastics. Pits on the side of the midline (off-midline pits) make one think of an acne inversa.

1st choice: sinusectomy

Since these fistulas are often very scarred, often only sinusectomy offers optimal chances of healing. Access is through a small incision at the upper end of the fistula or the narrow excision of the "pimple". The pits can be punched out with 2 - 3 mm or vaporized with laser. The stability of the gluteal fold is maintained.

Alternative: Pit Picking and SiLaC

Laser sclerotherapy can be a sensible alternative for long, slender fistula ducts. 


Type II B: Long fistula with blind sac over the lower spine

The flat, large volume Pilonidal Sinus (Type IV according to Tezel)

Picture of a Pilonidal Sinus with a big dummy bag
Schematic drawing Pilonidal Sinus Type IIB

Externally, the extension of this type of fistula is often not obvious. Ultrasound images are therefore particularly important for type II B Pilonidal Sinus . With good planning, unpleasant surprises can be avoided during surgery.

1st choice: laser sinusectomy, if necessary endoscopically assisted
Many surgeons are convinced that such a fistula can only be treated radically. We see it differently. With the Dios Blue laser, endoscopic visualizationand experience,it can be removed Removal via lateral accesses of about 2 - 3 cm.

Alternative: complete excision and reconstruction according to Karydakis

Type III: Secondary fistula after sacral pits

The fistula resulting from a congenital retraction of the skin above the tip of the coccyx

Scheme Pilonidal Sinus Type III new 2020
Schematic drawing Pilonidal Sinus Type III

5 % aller Neugeborenen haben eine Einziehung der Haut über der Steißbeinspitze (Sakralgrübchen, engl. sacral dimple). Nur < 0,1 % dieser Kinder entwickeln sekundär eine Fistel. Spinale Fehlbildungen sind extrem selten (Kucera, Wilson). Bei Ausdehnung zur Analregion kann man sie mit Analfisteln verwechseln.

1. sinusectomy

Since these fistulas are often very scarred with a palpable hardened strand and retraction of the skin, only sinusectomy offers good chances of healing.

We would advise against radical surgery or FiLaC/SiLaC for these fistulas. In the area between the tip of the coccyx and the anus, wound healing is often particularly laborious and protracted.

Type V to Tezel

Relapse of a Pilonidal Sinus

Chronic form of the pilonidal sinus, after previous operation

If the fistula is present again: The true recurrence, i.e. the reappearance of a pilonidal sinus from the pit to the fully developed fistula, is possible but rare. The types I - III of our classification therefore play less of a role in recurrence.

Our Pilonidal Sinus picture gallery therefore shows the common group IV fistulas. The wound has either never completely healed or pain or openings have recurred after supposed healing. The germ cell for these recurring symptoms are often already in the course of wound healing stored hairs.

The "real" recurrence ...

... is rare!

Wikipedia writes: "A relapse (Latin recidere "to relapse") is the recurrence ("relapse") of a disease or mental disorder."

Recurrence requires that the disease was previously cured. Thus, in a true recurrence, the disease process runs again from beginning to end.

It is basically possible for new pits to form as the cause of a Pilonidal Sinus .  

In most cases the recurrence is either a persisting fistula with incomplete removal of the fistula tract or overlooked "pits" or a poorly healed surgical wound ("pseudorecurrence" type IV of our classification).

Image of a reappeared Pilonidal Sinus
Recurrence, starting from a most inconspicuous pit below the old scar. The blue marked skin discoloration was caused by an allergy to iodine ointment, similar skin changes were also found on the back.
Picture of a minimally invasive removed Pilonidal Sinus (pit-picking)
Removed fistula tract, the arrow points to the causative primary opening (pit), the small particle next to it is the channel punched out during pit picking

Type IVa: Tubular pseudo-recurrence

When hairs impale themselves in the scar at the bottom....

Scheme Pilonidal Sinus Type IV new 2020
Schematic drawing Pilonidal Sinus Type IV A

This form of fistula can occur after all types of previous surgery. The cause is almost always the ingrowth of hair from the lower pole of the wound. Only later does an opening reappear on the upper edge, when the inflammation has worked its way under the scar. 

1st laser sclerotherapy (SiLaC): In the early stages, scraping out the fistula tract and laser sclerotherapy may be sufficient. In this situation, laser epilation is an essential part of the treatment concept.

2. sinusectomy

In many cases, the removal of the fistula tract through the existing openings with radiofrequency scalpel or laser is a goal-oriented treatment.

3. excision and Karydakis plastic

Alternatively we recommend the asymmetrical closure according to Karydakis.

Type IVb: spindle-shaped or oval pseudo-relapse

If loose hair or textile particles prevent healing...

Schematic drawing Pilonidal Sinus Type IV B
Schematic drawing Pilonidal Sinus Type IV B

This form of fistula occurs mainly after the spindle-shaped excision with open wound treatment. The cause is the ingrowth of hairs from around the wound. Broken off hairs collect under the skin.

The mechanical stimulus prevents permanent healing. Usually the wound closes again and again, but tears open again at every opportunity. Physical rest can not change this.

1. sparingly peeling off the hypergranulations ("wild meat"), taking the trapped hair with the Dios Blue Laser Close shaving in the post-treatment and laser epilation ensure the treatment result.

2. excision and Karydakis plastic

Alternatively we recommend the asymmetrical closure according to Karydakis.

Pilonidal Sinus and cancer - Can a pilonidal sinus become malignant?

Rare, but life-threatening...


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Squamous cell carcinoma of the rima ani
Squamous cell carcinoma of the rima ani

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Healing process (before - after - Pilonidal Sinus pictures)

Finally, we show Pilonidal Sinus pictures of the course of treatment. Basically, each "case" is an individual case, so that the procedure and treatment result are not easily transferable to future treatments. However, you can see that very good treatment results are possible without radical surgery.

Patient 26 years, no previous surgery, type I A fistula

Pilonidal Sinus Type I A
Pilonidal Sinus Type I A, deep, solitary pit, 2 cm long, scarred fistula. Sinusectomy performed.
Pilonidal Sinus Type I A, smooth, stable scar
Pilonidal Sinus Type I A, smooth, stable scar at the end of treatment.

Patient 30 years old, no previous surgery, type II A fistula

Pilonidal Sinus with numerous primary openings
Type II A fistula, before surgery
Picture after Pit Picking Operation
Fistula removed during pit picking surgery
IMG 20200703 WA0002

Patient 37 years, type I B fistula as mixed form to acne inversa

Acne inversa
Presentation for acute pain with diffuse inflammation of soft tissues
Decrease of inflammation after antibiotics - treatment 2 weeks
1 week after surgical removal with Karydakis - plastic, still clear. Swelling (seroma)
2 weeks after surgery, swelling largely gone, scar stable

Patient 26 years old, type I B fistula with 2 pits, first presentation with abscess

Acute pilonidal abscess, severe pain for 2 days
After the inflammation has subsided
Inflammation-free condition 2 weeks after abscess puncture
Picture of the course of treatment Situation after pit picking and sinusectomy
Wounds after pit picking and sinusectomy
Picture of the removed fistula
Picture of the removed fistula. In the lower left corner of the picture a small fragment was left, which was removed as a second fragment. Clearly visible the enclosed hairs

Patient 38 years, longstanding known fistula type II A

Picture of a long existing Pilonidal Sinus
Pilonidal Sinus Type II A, numerous openings, strong scarring after years of progression
Picture of a healed Pilonidal Sinus
Healing result after sinusectomy and 3 x laser epilation

Patient 24 years, no previous surgery, type II A and III combined

Photo of 2 independent Pilonidal Sinus on the same patient
Double fistula type IIA and type III
Wounds healed stably after Pilonidal Sinus surgery.
Healing condition after pit picking and sinusectomy. Image after shaving, no laser epilation so far.

Patient 23 years old, type IV B fistula, first presentation with non-healing wound

Type IV B praeop
Purulent, non-healing wound after conventional radical surgery
Completion of wound healing after laser OP
Stably healed condition after fistulectomy and 6 x laser treatment

Patient 35 years, type IV B fistula, previously 3 operations in 10 years, wound never healed

Pilonidal Sinus Wound does not heal
Stably healed condition after fistulectomy and 6 x laser treatment
Pilonidal Sinus cured
Stably healed condition after fistulectomy and 6 x laser treatment

Patient 17 years, recurrence after Limberg plastic surgery

Limberg plastic after surgery, wound sutured
Limberg plastic postoperative, with horizontal drainage, suture in the midline
Renewed suppuration from the scar
Limberg plastic with type IV a recurrence and purulent secretion
Wound heals after surgery and laser
Limberg plastic healing after fistulectomy and 4 x laser epilation

Patient 28 years, double fistula

IMG 5838
Image after removal of two independent fistulas to the left and right side

Patient 25 years, type II A fistula

Pilonidal Sinus before surgery
Type II A Initial findings
Type II A final result
Type II A final result

Patient 19 years, type II A fistula

Many small holes above the coccyx
Type II A fistula, before surgery
Type II A fistula with numerous pits after pit picking and sinusectomy.
Type II A fistula with numerous pits, after pit picking and sinusectomy

Inflammation above the coccyx, but no Pilonidal Sinus

Not every wound or inflammation in the buttock crease is a Pilonidal Sinus. After so many sinus pilonidalis images, here are illustrations of some important differential diagnoses.

Rhagade of the Rima ani (butt fold)

Superficial tears

A raghade is a wound that looks like a tear or a cut. It always affects only the most superficial layer of the skin, the epidermis.

In patients who have already undergone surgery using the "Metzger" method, the cause is probably a lack of stability of an inelastic scar in the face of the strong shear forces.

But even in patients who have never been operated on before, such raghaden occur. The most common form of psoriasis is then a limited form of psoriasis.

Rhagades can lead to a usually low secretion of yellowish secretion (fibrin), so that one mistakenly suspects a suppurating fistula.

The treatment is conservative. In acute phases cortisone and antibacterial creams (e.g. Fucicort®) help.

Infected atheroma (groat pouch)

Inflamed sebaceous gland

An atheroma is a cystic accumulation of a pasty secretion. The cause is a clogged gland of the skin. It can remain asymptomatic for a long time, and then become inflamed for no apparent reason.

In these cases, the inflammatory reaction of the surrounding tissue often reaches a magnitude that is much larger than the cyst itself. A kind of pus pimple is sometimes found centrally in the "bulge". Typical pits in the midline are missing.

These cysts can also be removed through relatively small incisions, the probability of a relapse is lower than with the typical Pilonidal Sinus.

Atheroma pictures
Pronounced inflammation in atheroma

Acne inversa

Acne inversa (older name hidradenitis suppurativa) is a chronic fistulous disease that is found preferentially in the axilla, groin, perianal region and skin fold under the female breast.

The frequency (prevalence) is given as 0.05% to 4.1%. The average time from the first symptoms to diagnosis is 7.1 years.

Acne inversa 1
Severe acne inversa Hurley III with pronounced scarring and numerous lateral openings
Mixed form of a pilonidal sinus with acne inversa
Mixture of a Pilonidal Sinus with the acne inversa (note lateral "off midline" pits, scarring)

The disease begins with inflammation of the hair follicles by lymphocytes, followed by loss of the sebaceous glands, congestion of the hair follicle, and finally bursting (follicle rupture) with penetration of the contents into the subcutaneous tissue.

The inflammation spreads without regard to anatomical barriers and the typical picture of numerous fistula openings with varying degrees of scarring, confluent fistulas and progressive tissue destruction develops. In the tissue, the inflammatory hormones interleukin-1 (IL-1), tumor necrosis factor (TNF) and many others are elevated.

There is a certain genetic disposition for these fistulas, in which a misregulation of the immune reactions is assumed. 

On the adjoining acne inversa pictures one can see the typical scarring, lateral openings and branching of the disease formerly also called hidradenitis suppurativa.

99% of all patients with acne inversa who have ever entered my practice are smokers. A cure for this systemic disease is only possible after smoking cessation. Surgery can remove existing foci and relieve abscesses, but cannot prevent recurrences.

New treatment approaches are laser treatment, the LAIGHT therapy, which was investigated in studies at the University of Mainz, and laser ablation.

There is often no way around a conventional excision.

Lichen (ruber) planus

Lichen ruber planus is a not so rare (prevalence 0.5 %) autoimmune disease of the skin and sometimes also of the mucous membranes. It is characterised by the formation of slightly raised skin rashes from coalescing individual lesions (papules). Net-like, whitish deposits, the so-called Wickham's stripes, can be seen on the surface.

The cause is still unclear, sometimes there is a connection with liver disease and stress. There is often a pronounced itching. In 90 % of patients, the disease heals within 2 years. Cortisone and other immunomodulators (Protopic®) are used therapeutically, sometimes also first-generation antihistamines. In some patients, once-weekly administration of enoxaparin (a heparin-like drug used for thrombosis prevention) is effective.

Differential diagnosis for itching Pilonidal Sinus
Lichen ruber planus of the gluteal fold

Anal fistula

A Pilonidal Sinus practically never finds connection to the anal canal or intestine. Here you will find information about anal fistula and the treatment of anal fistula.