Get rid of the pilonidal cyst!

"Showered - Blood in the water - Checked - Holes in the coccyx - Googled - Oh no, a huge chunk of flesh must be cut away...!"

Source: Arztbewertungsportal Jameda

If you are looking for specific solutions for your pilonidal cyst or tailbone fistula, you will find a wealth of valuable information on the following pages to help you keep track of the various surgical techniques. You may then find that a "huge chunk of meat" does not have to be cut away at all, but that a minimally invasive measure is completely sufficient. A prerequisite is an examination by one of the few surgeons who are familiar with minimally invasive fistula surgery and can individually assess the success of pit picking and the like.

Standard surgery - the big hole on the buttocks

As a standard procedure for pilonidal cyst and tailbone fistulas, radical cutting of the cyst and the fistula system with open wound healing is almost exclusively performed worldwide and also in Germany. This means that the wound is not sutured up, but instead covered with tamponades and must slowly heal "openly", as this is expected to produce better long-term results. The procedure is simple and quick from the technical point of view. It is usually performed under anaesthesia, and patients often spend 1 to 2 days in a hospital.

For the patient this means:

The wound must be showered daily and a new tamponade applied. Due to the localisation of the wound, it is difficult to change the dressing independently, so an assistant is necessary at least in the first few weeks.  Sitting and lying on the back is not possible in the first time after surgery, the wound also causes pain, which requires the regular use of painkillers, especially before changing dressings.

Hygienically, it's all such a thing. If the dressing is saturated with wound secretion, it should also be applied freshly in between, then the assistant must also be within reach. Wound secretion can be found in underwear and favourite jeans, possibly also on the bed sheet. Even if the wound is well cared for, it can occasionally smell something. Frequently the skin in the wound environment reacts to wound secretion and plaster material, becomes sore and develops redness, itching and red spots.

Everyday activities are out of the question, at least in the first few weeks. Sport and other leisure activities are not possible, the average time of incapacity for work is one month, or longer depending on the profession. 

Statistically, wound healing takes 1.5 to 3 months.  However, there are also known cases in which patients have had to struggle with their wounds for up to a year or longer.

Apart from the unpredictable duration of wound healing, this does not have to go without complications. It can stagnate, which means that nothing happens over a longer period of time, the wound doesn't want to get smaller. Or, for example, skin bridges are formed between the wound edges. This is an unmistakable sign that the body has surrendered in terms of wound healing.  A new surgical intervention is necessary, which not only throws the patient back in time but can also wear him down psychologically.

Once the wound has finally healed, a nasty surprise can occur after months or even years: The pilonidal cyst and fistula have returned, which is the case in up to 35% of patients undergoing surgery using this method.

Surgery of the pilonidal cyst as 70 years ago or rather minimally invasive?

The radical cutting out of the pilonidal cyst and tailbone fistula system is a surgical method that has been carried out for 70 years in an almost unchanged technique.

Those who are affected by a pilonidal cyst and fistulas and inform themselves about Google will sooner or later come across indications that much smaller interventions for the treatment of the fistula are also possible, e.g. pit picking. Minimally invasive fistula procedures have excellent results in experienced surgeon's hands. Thus, in up to 80% of cases, pit picking leads in a short time to a permanent elimination of the problem with a low impairment on the patient, who can usually resume their normal daily activities after 0 - 1 day.

Lord Lucan, Trephine surgery 1, CC BY-SA 4.0

Table of contents

Get rid of the pilonidal cyst!

Pilonidal cyst – what is it?

The frequency of pilonidal cysts and tailbone fistulas

Causes of pilonidal cysts and tailbone fistulas

Pilonidal cysts not only occur on the buttocks

Diseases that can appear like a pilonidal cyst or tailbone fistula

Symptoms of the pilonidal disease

How is a pilonidal cyst diagnosed?

Stage-adapted treatment of the pilonidal disease

Treatment methods for pilonidal cysts

 

Minimally invasive procedures

Phenol injections according to Maurice and Greenwood

Proceeding according to Lord and Millar

Pit Picking according to Bascom (Bascom I)

Procedure according to Moshe Gips

Sinusectomy

Traditional procedures

Excision with open wound treatment

Excision, marsupialisation of wound edges and open wound treatment

Excision with primary midline suture

Plastic procedures

Plastic closure with Z-plastic

Plastic closure according to Karydakis

Cleft-lift procedure (Bascom II)

Plastic closure according to Limberg

Laser application in pilonidal disease

Recurrence prophylaxis - Preventing new tailbone fistula

Rare complications of pilonidal disease

 

Updates

Laser hair removal for relapse prevention of pilonidal disease

Risk factors for postoperative wound healing troubles and recurrence of fistula formation after coccyx fistula surgery

Exact evaluation of the extension of pilonidal fistula and cyst with ultrasound

Family History of Pilonidal Sinus: Earlier Onset of Disease and 50 % Long-Term Recurrence Rate

  

Pilonidal cyst – what is it?

The pilonidal cyst ("pilus": hair) is an acute or chronic inflammation in the subcutaneous fatty tissue, predominantly in the region of the coccyx, i.e. at the upper end of the bottom fold. Commonly, the disease is usually referred to as tailbone fistula; less common terms are pilonidal sinus, pilonidal disease, hair nest pits and hair fistula. The disease was first described in 1833. The frequency of the pilonidal cyst and tailbone fistula shows an increasing tendency for unknown reasons.

Three types of fistula are distinguished: the accidentally discovered form, which does not cause any discomfort, the acute abscess formation and the chronic form. Usually granulation tissue, which is inferior connective tissue, hair and cell detritus, is found in the cyst-shaped sinus. The latter is a mushy, unstructured and usually greasy mass that develops due to an inflammatory melting of tissue.

For the development of a pilonidal cyst several factors must coincide, whereby the hair roots in the area of the gluteal fold play a decisive role. More details can be found in the chapter "Causes off pilonidal cysts". Young men of dark hair type develop a coccyx fistula disproportionately frequently.

There are a variety of treatment methods for the pilonidal cyst and its fistula. The most common method is to generously cut out the affected area with an open wound treatment. This means that the wound is not sutured, but provided with tamponades that have to be changed daily. The procedure is safe, but for those affected it means months of healing with correspondingly long restrictions for leisure activities and, if necessary, time off work. "Safe" means that the procedure is not risky and also quick, but it does not protect against recurrences, i.e. the recurrence of the pilonidal cyst and fistula.

Literature sources:

Anderson NP (1947) Cysts, sinuses and fistulas of dermatologic interest. J Am Med Assoc 135:607– 612
Da Silva JH (2000) Pilonidal cyst: cause and treatment. Dis Colon Rectum 43:1146–1156
Hull TL, Wu J (2002) Pilonidal disease. Surg Clin North Am 82: 1169-1185

Frequency of pilonidal cysts and tailbone fistulas

In 2012, the incidence of pilonidal cysts and tailbone fistulas in Germany was around 48/100,000 inhabitants. For unknown reasons, the number of people affected by fistulas is increasing. This is shown by figures collected from the German Armed Forces (mainly young men): in 1985 the figure was 30/100,000, but rose to a remarkable 240/100,000 in 2007.

The tailbone fistula is usually noticeable between the 2nd and 3rd decade of life, mainly in men below the age of 40. Men are affected 2.2 times as often as women. In 2013, a study was conducted to determine whether hormone levels might play a role as risk factors for the development of a fistula. Hormone levels were compared in men with and without tailbone fistula, and no differences were found. However, women with a tailbone fistula had elevated prolactin levels (prolactin is produced in the pituitary gland, especially during pregnancy and lactation).

Pilonidal cysts and tailbone fistulas do not necessarily cause symptoms such as pain, abscesses or leakage of wound secretion or pus. Sometimes the cysts and fistulas are simply present, do not cause any symptoms and are discovered by chance. There are also figures for this: During the Second World War, over 77,000 American soldiers underwent pilonidal sinus surgery, and another 9000 were found to have tailbone fistulas without any symptoms. A more recent study from Turkey showed that 8.8% of 1,000 soldiers had a fistula during the initial examination, 4.8% had symptoms and 4.0% had no symptoms.

The pilonidal cyst occurs predominantly in people of European descent, rarely in black-skinned people. In Asian countries the disease pattern is rarely observed, in China it is said to be completely unknown.

Literature sources:

Akinci OF, Bozer M et al (1999) Incidence and aetiological factors in pilonidal sinus among Turkish  soldiers. Eur J Surg 165:339–342

Casberg, MA (1949) Infected pilonidal cysts and  sinuses. Bull U S Army Med Dep 9:493–496

Chijiwa T, Suganuma T et al (2006) Pilonidal sinus  in Japan maritime self-defense force at Yokosuka.  Mil Med 171:650–652

Da Silva JH (2000) Pilonidal cyst: cause and treatment. Dis Colon Rectum 43:1146–1156

Doll D, Friederichs J et al (2008) Surgery for asymptomatic pilonidal sinus disease. Int J Colorectal  Dis 23:839–844

Evers T, Doll D et al (2011) Trends in incidence  and long-term recurrence rate of pilonidal sinus  disease and analysis of associated influencing  factors. Zhonghua Wai Ke Za Zhi 49:799–803

Lee HC, Ho YH et al (2000) Pilonidal disease in  Singapore: clinical features and management.  Aust N Z J Surg 70:196–198

Özkan Z, Aksoy N et al (2013) Investigation of the relationship between serum hormones and pilonidal sinus disease: a cross-sectional study. Colorectal Dis 16:311–314

Sondenaa K, Andersen E et al (1995) Patient characteristics and symptoms in chronic pilonidal sinus disease. Int J Colorectal Dis 10:39–42

Causes of pilonidal cysts and tailbone fistulas

Until the middle of the 20th century, it was assumed that the pilonidal cyst was congenital and the development of the fistula already took place in the embryo.

• Congenital fistulas of the coccyx do indeed occur:
• In rare cases, a pilonidal cyst in the fetus can be visualized by ultrasound as part of a prenatal examination.
• Newborns born with spinal cord and spinal canal anomalies often show a pilonidal cyst.
• Some medications taken during pregnancy can cause a pilonidal cyst in the newborn. These include, for example, the high-dose intake of phenytoin, a drug for the treatment of epilepsy.
• Another argument in favour of a genetic predisposition would be that a family history of pilonidal cyst can be observed. In a family history, the first symptoms often appear very early and the fistulas of the tailbone tend to reappear after treatment.
• Another congenital problem is that the pilonidal cyst is always located in or immediately near the midline of the buttocks region, where problems in the development of the fetus often occur during the embryonic period.

However, there is also some evidence against the assumption that the pilonidal cyst is exclusively congenital:

• An inflamed pilonidal cyst is rarely observed before puberty, and if it does, it occurs 4.5 times more frequently in boys than in girls.
• Another argument against this is that in the case of malformations of the spinal cord and spinal canal, the hair nest of the pilonidal cyst does not contain any scattered skin appendages such as sweat or sebaceous glands, as one might expect with a congenital problem.
• Nor does the theory of congenital tailbone fistula explain why in the majority of cases the disease only becomes apparent during puberty and then predominantly occurs in men with a stronger fat cushion over the coccyx

.

Acquired disease with a questionable genetic predisposition

Pilonidal cysts and tailbone fistulas are nowadays regarded as a disease acquired during puberty in which there may be a genetic predisposition. The fistula formation is triggered by the rubbing movements of the buttocks, which causes broken hair to twist into the skin. This creates depressions in the skin that can contain hair, the so-called pits.

Nartoun, SinusPilonidalis, marked as public domain

The horny scales of the hair act like barbs, whereby the hair can penetrate deeper and deeper into the subcutaneous fatty tissue. This is where a foreign body granuloma develops.

Foreign body granulomas do not heal spontaneously. They do not necessarily cause symptoms (asymptomatic form) but can become infected. The consequences are discomfort when sitting, a feeling of pressure or even small, bloody secretions (chronic form) as well as the abrupt development of abscesses (acute form).

The development of the tailbone fistula is favoured by additional factors.  These include strong hairiness, overweight, excessive sweating, a strong fat cushion over the tailbone as well as a deeply absorbed bottom fold. A predominantly sedentary activity also has a favourable effect. This has led to the designation "jeep´s disease" among soldiers since during the Second World War between 1942 and 1945 more than 77,000 American soldiers fell ill with a tailbone fistula.

It is often claimed that a lack of personal hygiene is an additional risk factor. However, studies have shown that hygiene behaviour has no influence on the formation, abscess formation or recurrence of the tailbone fistula.

Literature sources:

Doll D, Petersen S (2008) Trauma is not a common origin of pilonidal sinus. Dermatol Surg  34:283–284

Efrat Z, Perri T et al (2001) Early sonographic detection of a ‚human tail’: a case report. Ultrasound  Obstet Gynecol 18:534–535

Spivak H, Brooks VL et al (1996) Treatment of  chronic pilonidal disease. Dis Colon Rectum  39:1136–1139

Badawy EA, Kanawati MN (2009) Effect of hair removal by Nd: YAG laser on the recurrence of pilonidal sinus. J Eur Acad Dermatol Venereol  23:883–886

Goldberg RB, Fish B et al (1978) Bilateral femoral  dysgenesis syndrome: a case report. Cleft Palate J  15:1263–1268

Yang TS, Chi CC et al (1978) Diphenylhydantoin  teratogenicity in man. Obstet Gynecol 52:682– 684

Akinci OF, Bozer M et al (1999) Incidence and aetiological factors in pilonidal sinus among Turkish  soldiers. Eur J Surg 165:339–342

Sondenaa K, Andersen E et al (1995) Patient characteristics and symptoms in chronic pilonidal sinus disease. Int J Colorectal Dis 10:39–42

Doll D, Matevossian E et al (2009) Family history  of pilonidal sinus predisposes to earlier onset of  disease and a 50% long-term recurrence rate. Dis  Colon Rectum 52:1610–1615

Chamberlain JW, Vawter GF (1974) The congenital origin of pilonidal sinus. J Pediatr Surg 9:441– 444

Golladay ES, Wagner CW (1990) Pediatric pilonidal disease: a method of management. South  Med J 83:922–924

Dahl HD, Henrich MH (1992) Light and scanning  electron microscopy study of the pathogenesis  of pilonidal sinus and anal fistula. Langenbecks  Arch Chir 377:118–124

Stelzner F (1984) Die Ursache des Pilonidalsinus und der Pyodermia fistulans sinifica. Langenbecks Arch Chir 362:105–118

Balik O, Balik AA et al (2006) The importance of local subcutaneous fat thickness in pilonidal disease. Dis Colon Rectum 49:1755–1757

Bascom J (1980) Pilonidal disease: origin from follicles of hairs and results of follicle removal as treatment. Surgery 87:567–572

Patey DH (1969) A reappraisal of the acquired  theory of sacrococcygeal pilonidal sinus and an  assessment of its influence on surgical practice.  Br J Surg 56:463–466

Benedetto AV (2010) Commentary: hair and pilonidal sinus disease. Dermatol Surg 36:92–93

Sondenaa K, Andersen E et al (1995) Patient characteristics and symptoms in chronic pilonidal sinus disease. Int J Colorectal Dis 10:39–42

Arda IS, Guney LH et al (2005) High body mass index as a possible risk factor for pilonidal sinus disease in adolescents. World J Surg 29:469–471

Bolandparvaz S, Moghadam Dizaj P et al (2012)  Evaluation of the risk factors of pilonidal sinus:  a single center experience. Turk J Gastroenterol  23:535–537

Conroy FJ, Kandamany N et al (2008) Laser depilation and hygiene: preventing recurrent pilonidal sinus disease. J Plast Reconstr Aesthet Surg  61:1069–1072

Sievert H, Evers T et al (2013) The influence of lifestyle (smoking and body mass index) on wound healing and long-term recurrence rate in  534 primary pilonidal sinus patients. Int J Colorectal Dis 28:1555–1562

Favre R, Delacroix P (1964) Apropos of 1,110 cases of pilonidal disease of coccy-perineal localization. Mem Acad Chir (Paris) 90:669–676

Akinci OF, Kurt M et al (2009) Natal cleft deeper  in patients with pilonidal sinus: implications for  choice of surgical procedure. Dis Colon Rectum  52:1000–1002

Corman M (1982) Classic articles in colonic and  rectal surgery. Louis A. Buie, M.D. 1890–1975:  jeep disease (pilonidal disease of mechanized  warfare). Dis Colon Rectum 25:384–390

Casberg, MA (1949) Infected pilonidal cysts and  sinuses. Bull U S Army Med Dep 9:493–496

Pilonidal cysts not only occur on the buttocks

The pilonidal cyst usually occurs in the region of the coccyx, but occasionally also in other regions of the body: in the belly button, the armpit, on the penis, between the fingers (in hairdressers) and toes, in the area of the chest and also behind the ears.

Barber´s disease

In hairdressers, the pilonidal cyst between the fingers is recognised as an occupational disease. This disease, also known as "interfinger hair pocket disease", hairdresser's disease or interdigital sinus pilonidalis (interdigital = between the fingers) is very rare.

The reason for this is the penetration of cut foreign hair into the finger gaps with the formation of granulomas, cysts and fistula ducts. The most frequently affected is the space between the 3rd and 4th fingers of a hand, but other spaces and both hands can also be affected at the same time. A similar occupational disease is known in sheep shears due to the penetration of wool and in milking cow hair.

Only the complete surgical removal of granuloma and fistula system can be considered as a treatment measure. The most important preventive measures are regular checks of the spaces between the fingers and the removal of any foreign hair that may be present.

Literature sources:

Colapinto ND (1977) Umbilical pilonidal sinus. Br  J Surg 64:494–495

Eryilmaz R, Sahin M et al (2005) Umbilical pilonidal sinus disease: predisposing factors and treatment. World J Surg 29:1158–1160

Fazeli MS, Lebaschi AH et al (2008) Evaluation of the outcome of complete sinus excision with reconstruction of the umbilicus in patients with umbilical pilonidal sinus. World J Surg 32:2305– 2308

Kareem T (2013) Outcomes of conservative treatment of 134 cases of umbilical pilonidal sinus.  World J Surg 37:313–317

McClenathan JH (2000) Umbilical pilonidal sinus.  Can J Surg 43:225

Khan AB, Scott RN (1992) Pilonidal abscess of the  penis. Br J Urol 69:437–438

Ballas K, Psarras K et al (2006) Interdigital pilonidal sinus in a hairdresser. J Hand Surg Br 31:290– 291

Eryilmaz R, Okan I et al (2012) Interdigital pilonidal sinus: a case report and literature review. Dermatol Surg 38:1400–1403

Patey DH, Scarff RW (1948) Pilonidal sinus in a barber’s hand with observations on postanal pilonidal sinus. Lancet 2:13

Stern PJ, Goldfarb CA (2004) Interdigital pilonidal  sinus. N Engl J Med 350:e10

Grant I, Mahaffey PJ (2001) Pilonidal sinus of the  finger pulp. J Hand Surg Br 26:490–491

Ferdinand RD, Scott DJ et al (1997) Pilonidal cyst  of the breast. Br J Surg 84:784

Yokoyama T, Nishimura K et al (2007) Pilonidal sinus of the supraauricle area. J Eur Acad Dermatol Venereol 21:257–258

Diseases that can appear like a pilonidal cyst or tailbone fistula

The pilonidal cyst and tailbone fistula can be confused with a number of other diseases. These primarily include fistula formation from the anus (anal fistulae) and fistulae that can occur in chronic inflammatory intestinal diseases such as Crohn's disease. Fistula diseases in the buttocks can also be caused by acne inversa. This is a chronic skin disease based on inflammation of the sebaceous glands and hair roots.

Rhagades can also imitate a pilonidal disease. These are narrow, slit-shaped tears in the skin due to overstretching. Psoriasis is also one of the differential diagnoses.

Literature sources:

Steinemann D, Dindo D et al (2011) Pilonidalsinus und Analfistel. Coloproctology 33:160–170

Breuninger H (2004) Treatment of pilonidal sinus  and acne inversa. Hautarzt 55:254–258

Stelzner F (1984) Die Ursache des Pilonidalsinus und der Pyodermia fistulans sinifica. Langenbecks Arch Chir 362:105–118

Laffert M von, Stadie V et al (2011) Morphology  of pilonidal sinus disease: some evidence of its  being a unilocalized type of hidradenitis suppurativa. Dermatology 223:349–355

Jansen T, Wolff H et al (1996) Eruptive vellus hair  cysts. Hautarzt 47:378–381

Alrawashdeh W, Ajaz S et al (2008) Primary anal  pilonidal disease. Colorectal Dis 10:303–304

Accarpio G, Davini MD et al (1988) Pilonidal sinus  with an anal canal fistula. Report of a case. Dis  Colon Rectum 31:965–967

Marra B, Fantini C et al (2005) Management of sacrococcygeal chordoma mimicking a pilonidal sinus: report of a case. Int J Colorectal Dis 20:388– 389

Fitzgerald JE, Lepore M (2012) Idiopathic calcinosis cutis infection as an unusual mimic of pilonidal abscess. ANZ J Surg 82:758–759

Gupta PJ (2008) Tubercular infection in the sacrococcygeal pilonidal sinus – a case report. Int  Wound J 5:648–650

Anscombe AR, Hofmeyr J (1954) Perianal actinomycosis complicating pilonidal sinus. Br J Surg  41:666

Alexiou GA, Sfakianos G et al (2012) Myxopapillary ependymoma of the sacrococcygeal region  presenting as a pilonidal sinus. Pediatr Neurosurg  48:64–65

Symptoms of pilonidal disease

Pilonidal cyst and tailbone fistula can occur in three different forms with correspondingly different symptoms:

• asymptomatic
• chronic
• acute

Asymptomatic pilonidal cyst

The symptom-free tailbone fistula is characterized by the presence of one or more pits in the bottom fold. There are no signs of inflammation and no secretions. Since it does not cause any discomfort or secretion, this form of pilonidal sinus is often discovered by chance. Once the fistula is there, it does not heal spontaneously, normally it will last a lifetime.

Nartoun, SinusPilonidalis, marked as public domain

Since the spontaneous progression of the fistula disease is not inevitable, there are now two possibilities: Those affected have a fistula for a lifetime without ever developing symptoms. Or the fistula disease eventually changes into one of the following two forms and then requires treatment.

It is not possible to predict when an existing tailbone fistula will develop symptoms for the first time. Often there are several years between the occurrence of pits and the first symptoms. The MVZ St. Marien Cologne, Germany recently reported a tailbone fistula that existed for more than 30 years until it developed symptoms. The fistula was removed by minimal-invasive surgery.

Chronic pilonidal disease

Typical for the chronic pilonidal disease is the presence of pits with bloody purulent secretion. Secretion can be permanent or recurrent, i.e. occasional rest. Often a further fistula opening develops near the pits towards the buttock, the so-called secondary fistula, which indicates an inflammatory process that has existed for a long time.

   GiggsHammouri, Pilonidal cyst, CC BY 3.0

                                                                        

Acute Pilonidal disease

This has led to the formation of an abscess in the pilonidal cyst. The abscesses almost always lie to the side of the gluteal fold, rarely in the area of the pits that are located in the gluteal fold. These abscesses are recognizable by a painful, reddened swelling that often develops within a short time. If the abscesses break open outwards (this is called spontaneous perforation) or if they are surgically opened, pus is drained.

Jonathanlund, Pilonidal abscess, CC BY-SA 4.0

                                                    

Literature sources:

Sondenaa K, Andersen E et al (1995) Patient characteristics and symptoms in chronic pilonidal sinus disease. Int J Colorectal Dis 10:39–42

Doll D, Friederichs J et al (2008) Time and rate of  sinus formation in pilonidal sinus disease. Int J  Colorectal Dis 23:359–364

Brook I (1989) Microbiology of infected pilonidal  sinuses. J Clin Pathol 42:1140–1142

Pearson HE, Smiley DF (1968) Bacteroides in pilonidal sinuses. Am J Surg 115:336–338

How is a pilonidal cyst diagnosed?

The diagnosis of a tailbone fistula is an eye diagnosis. This means that the visible and palpable changes of the pilonidal disease are so typical that experienced examiners can usually make the diagnosis without major technical effort.

The pits or fistula openings in the gluteal fold are relatively easy to find and can be recognised by small, funnel-shaped retractions of the skin, possibly with sprouting hairs. If a chronic pilonidal cyst is present, depending on its size, it is already visible by a slight protrusion in the immediate vicinity of the gluteal fold; smaller ones are usually palpable as a circumscribed hardening under the skin. Depending on the inflammatory state of the cystic sinus, bloody-purulent secretion empties from the pits when pressure is applied to it.

Simple X-ray examination does not play a role in imaging procedures. Computed tomography and magnetic resonance imaging are generally dispensable, but can occasionally be helpful for surgical planning in complex plastic surgery.

A fast and uncomplicated, radiation-free imaging for the representation of the pilonidal cyst is possible with an ultrasound examination. The localisation and extent of a pilonidal cyst can be easily visualised with it, usually also the connection to the pits under the skin in the subcutaneous fatty tissue.

Pilonidal cyst in ultrasound image  (c) MVZ St. Marien Cologne, Germany

Literature sources:

Taylor SA, Halligan S, Bartram CI. Pilonidal sinus disease: MR imaging distinction from fistula in ano. Radiology. 2003;226 (3): 662-7

Mentes O, Oysul A, Harlak A et-al. Ultrasonography accurately evaluates the dimension and shape of the pilonidal sinus. Clinics (Sao Paulo). 2010;64 (3): 189-92

Imanishi H, Tsuruta D, Nomura N et-al. Clinical usefulness of ultrasonography in interdigital pilonidal sinus. J Cutan Med Surg. 2012;16 (3): 194-6

Adams CI, Petrie PW, Hooper G. Interdigital pilonidal sinus in the hand. J Hand Surg Br. 2001;26 (1): 53-5