Umbilical Pilonidal Sinus: a Case Report and Systematic Review.

This is a 19 years old, male patient, known to have autism spectrum disorder with a prior umbilical hernia repair (when the patient was 6 years old). The patient presented to the out-patient clinic when he was 17 years of age with his parents, complaining of minimal umbilical serous discharges. Upon examination, the area had poor hygiene and villous hair all around the umbilicus. The patient was followed every 3 months with no noted changes, yet after 1 year of follow up, a small umbilical swelling 1x2 cm was noted with 2 pits and hemo-serous discharges with surrounding hair tufts, no hernial recurrence noted. The family was counselled on risks and benefits of conservative versus surgical excision, and they opted for surgical excision. The patient’s pre-operative laboratory workup was normal. Post-operatively, the patient was doing well with no complaints (e.g., pain or discharges), however after 2 weeks the patient developed a small hematoma that was aspirated, other than that the follows ups were unremarkable.

There was a total of 11 studies in Saudia Arabia of which only 2 were included, 122 studies worldwide were analysed, and 21 studies were included, with both searches Cochrane Central Register of Controlled Trials (OvidSP) yielded no results ( Figures 1 and 2 ). The Saudi Arabian 2 studies included a heterogenous group of 45 individuals, with 80% being males (n=36), the majority presenting with a complaint of episodic umbilical foul discharges and noted hair tufts in 73.3% (n=33), only one patient’s body mass index (BMI) was reported at 39.1 Kg/m2. Worldwide, there was a total of 681 individuals, 83.7% being males (n=570) with a mean age ± standard deviation (SD) of 26.7 ± 2 years of age, a mean BMI ± SD of 30 ± 2.5 Kg/m2, and mostly an ethnic background from Turkey (n=285) ( 5 , 6 , 8 , 9 , 13 , 16 , 19 , 20 ), Iraq (n=248) ( 7 , 10 ) and Iran (n=96) ( 12 , 15 ). The main presenting symptoms were umbilical pain and discharges, while upon assessment, 47.7 % (n=325) had hair body type (Hirsute) ( 7 , 8 - 10 , 12 , 13 , 17 , 21 , 25 , 26 ), 30.5 % (n=208) had deep navels ( 5 , 9 , 10 , 21 , 25 ), 17.1% (n=117) were overweight or obese (BMI > 25 Kg/m2) ( 7 - 9 , 17 , 24 , 25 ), 15.7% (n=107) had a positive family history of pilonidal sinuses ( 6 - 8 , 13 ), 11.6% (n=79) had poor personal hygiene (i.e., had a full body shower less than or equal twice per week), 10.6% (n=72) had history of other non-UPS ( 8 , 10 , 12 , 13 , 28 ) and 10.6% (n=72) reported tight clothes, regularly (i.e., more than or equal three times per week). Although, smoking was reported as significantly correlated with recurrence ( 6 ), it was only reported as a calculated variable in 5.7% (n=39) ( 8 ). In Saudi Arabi, one individual underwent abdomen computed tomography (CT), while the majority of cases were diagnosed clinically (i.e., the presence of umbilical discharges with or without peri-umbilical swelling, itchiness or pain, with an examination observed hair tuft or sinus). Similarly, worldwide radiological assessment was done if other diagnoses were suspected (e.g., umbilical hernia, patent urachal cyst or sinus, etc.). There were 12.5% (n=85) who underwent ultrasound ( 6 , 17 , 20 , 23 ), one CT fistulography ( 19 ) and one magnetic resonance imaging ( 17 ). The post-operative histopathology of the sinus showcases hair shafts, epithelial debris, keratin, chronic inflammatory infiltrate (secondary to the presence of hair shafts) and other manifestations (e.g., ulceration, giant cell reaction, congested vessels) ( 9 , 19 , 23 , 25 , 26 ). The Saudi Arabian group mainly underwent conservative management (i.e., local debridement, ensuring proper hair removal and regular dressing) with no reported recurrence. On the other hand, 650 individuals had clear management, while 31 individuals were unclear ( 13 ). Surgically, 142 individuals were included with the main techniques used being umbilectomy (with or without reconstruction) in 134 (94.3%), while when the sinus’s cavity was not in direct contact with the umbilical base, umbilicus-preserving sinus excision was done in 7 (4.9%) while one patient underwent laser therapy of UPS ( 5 , 6 , 9 , 10 , 12 , 15 - 17 , 19 , 20 , 22 - 28 ). The reported recurrence rate is 1.4% (n=2) ( 5 , 17 ). On the other hand, 508 individuals underwent conservative management by different local therapeutic measures with the main principle being ensuring complete hair removal with suggested different techniques (e.g., otoscopy or cryocone use) ( 14 , 18 ). There were 357 (70.2%) individuals who underwent local care, oral antibiotics and regular povidone dressing ( 5 , 6 , 8 , 9 - 11 , 14 , 15 , 18 , 21 ), 23 individuals with additional silver nitrite application, one individual with additional phenol (88%) cauterization ( 6 , 8 , 25 ), and a recurrence rate of 10.6%. In addition, 114 individuals had a mixture of petroleum jelly, henna powder and topical tetracycline for dressing with <1% and in a 3-group comparison by Sözen et al., (total 56) a group of 18 individuals had salt application as dressing, yielding the least recurrence ( 8 ). Cumulatively, the surgical management group yielded a recurrence rate of 1.4% while the conservative management group yielded 7.9%. This article presents a case report describing a 19-year-old male with a known history of autism spectrum disorder who presented with a complaint of recurrent, umbilical swelling. The patient’s unique neurodevelopmental background posed challenges in clinical assessment and management, necessitating a tailored approach to ensure optimal care. Surgical excision of the lesion was performed under local anesthesia while the patient was being cooperative and calm, histopathological testing confirmed the diagnosis of UPS. This case highlights the importance of considering UPS in the differential diagnosis of umbilical swellings (Al-Kadi et al., 2014; 4: 1. Saudi Arabia, 26 - 1 male (100%), N\A. 39.1. Obesity. Umbilical Foul-smelling discharge with periodic painful episodes. Clinical and radiological Contrast-enhanced, CT scan: Increased soft tissue density in the umbilical region with considerable enhancement, no visceral attachment. Surgical (Complete sinus excision and umbilical reconstruction). Preoperative: conservative measures. None exploration of the umbilicus was carried out using sterile cotton on a stick, with xylocaine spray 10% used in 3 cases. This was followed by removal of hair using non-toothed tissue forceps, and a solution of povidone iodine was prescribed to patients to use twice daily while lying down in supine position and sterile gauze on umbilicus as dressing. Local care with dressing, hair removal and oral antibiotics.

The study had a combined approach of a case report with an acquired parental and patient consent, and a Systematic review of literature in Saudi Arabia and Worldwide, abiding to Helsinki doctrine. The researchers involved, followed the Cochrane Review methods and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, with a PROSPERO authentication [ID: CRD420251121519]. The studies included were of patients with UPS of any age and gender, who underwent conservative or surgical management in Saudi Arabia and worldwide. There was a range of included study types (i.e., randomized and non-randomized studies, prospective and retrospective cohort studies, case-control studies and case reports). This review considered articles that have been conducted on human subjects and published in any language with patients who underwent either conservative (e.g., antibiotics) or surgical management. On the other hand, studies that were conducted on non-umbilical pilonidal cyst or sinus (non-UPS) patients (e.g., mammary pilonidal cysts), involved non-human subjects, duplicated data published in different articles or had an overall poor quality (i.e., unmentioned selection, diagnostic or therapeutic criteria). The electronic search for eligible studies was conducted using the Cochrane Central Register of Controlled Trials (OvidSP), PubMed, MEDLINE (ProQuest, Ann Arbor, MI, USA), and Web of Science (Clarivate) databases. In each case, all available publication until February 2025 were included in the analysis. Furthermore, we surveyed the reference lists of all eligible records and searched Google Scholar to identify any additional eligible records. The keyword groups were used in the search strategy were (Umbilical OR Umbilicus) AND (pilonidal cyst OR Sinus) with and without [AND (Kingdom of Saudi Arabia OR Saudi Arabia)]. These words were run in all the databases, and to prevent a very specific search outcome we used (Umbilical Pilonidal Cyst or Sinus) through Google Scholar, then (AA and OB) ensured proper studies listing. The search process involved importing articles and reference lists into Microsoft Excel, where duplicates were identified, reviewed manually, and eliminated. Subsequently, a three-step filtering process was employed, which entailed evaluating the records based on their title, abstract, and full text. The records were evaluated by two authors (O. B. and O. A.) for any relevance and in cases of disagreement, consensus was reached by discussion, and if necessary, a third researcher (A. B.) was consulted. If needed, further information was sought from the authors to clarify necessary details and acquire the missing data. The studies’ data extraction form included study-related variables (Author/s, year of publication, country of origin) and sample-related variables (age, ethnicity, body mass index, comorbidities, number of males, presenting complaints, diagnosis, radiological findings, interventions and recurrence) which were listed in an Excel sheet and filled by (O. B. and A. A.) to ensure revision if a discrepancy was noted. The Joanna Briggs Institute critical appraisal checklists were used to assess the included studies’ quality and evaluate the appropriate bias category (e.g., information bias, confounding, etc.) and the quality of the study design. Then, accordingly based on the risk of bias, each study was classified, for further information check [Supplementary Checklists].

Therefore, in this article we systematically reviewed all the literature on UPS in Saudi Arabia and worldwide to formulate a clinical picture, a possible management algorithm and report noted outcomes.

Umbilical pilonidal sinus (UPS) is a rare condition characterized by the formation of a sinus tract in the umbilical region, often associated with chronic inflammation and hair accumulation. This clinical entity is more commonly encountered at the natal cleft. However, due to its rarity and nonspecific presentation, UPS is frequently underdiagnosed, leading to delays in appropriate management ( 1 ). The condition typically presents with various symptoms (e.g., periodic umbilical swelling, pain and discharge) with noted several predisposing factors (e.g., poor hygiene, obesity, or excessive body hair). Due to the rarity of this condition, there are no standardized management guidelines and treatment is tailored to the clinical presentation, with cases managed either conservatively (i.e., local hair removal with proper hygiene) or surgically ( 2 ).

UPS is a rare and an underreported condition that impairs the patients’ quality of life and is often misdiagnosed as other umbilical pathologies (check the Diagnostic Process subsection). The current case report and systematic review highlight the diagnostic challenges and reviews the spectrum of management options, as Male sex, hirsutism, deep umbilicus, obesity, and poor hygiene were consistent risk factors. The diagnosis is usually clinical, but atypical presentations warrant consideration of alternative differentials and, when appropriate, radiological assessment. Management is best applied in a “Step-up” approach: risk factor optimization and conservative measures as first-line, with surgical excision reserved for recurrent or refractory cases. There is a necessity, secondary to scarcity of international data (including Saudi Arabia), in formulating a management approach based on local clinical evidence (e.g., societal norms and hygiene), to improve awareness and deliver consistent, patient-centred, evidence-based care.

UPS is a rare disease with an understated incidence that a few papers attempted to calculate, approximating it at 0.6% from Goodall (1995) ( 30 ). The pathophysiology starts with a hair’s abnormal eruption through the outermost skin layer, leading to its inversion, hair maturation, inflammatory cascade activation, granuloma and sinus formation. However, if skin flora’s bacteria were translocated to the sinus, it triggers peri-umbilical cellulitis which might lead to abscess formation. Clinically, UPS is more common in males with several correlated risk factors (i.e., hirsutism, deep navels, BMI >25 kg/m2, positive family history of pilonidal sinuses, poor personal hygiene, wearing tight clothes and smoking) that were derived from the analysis. The increased incidence in males could be driven by androgen-based villous hair growth after puberty, at a set pattern (e.g., involving the abdomen and back) and their higher incidence of hirsutism (i.e., increase hair formation would proportionally lead to increase epithelial debris and hairs accumulation within the sinus). Similarly, in correlation to UPS formation being overweight increases skin creases, sweating and epithelial debris accumulation in the navel, having deep navels, poor personal hygiene and wearing tight clothe, while smoking was noted to be correlated more with recurrence rather than to be as an independent risk factor ( 5 , 6 ). The diagnosis of UPS is clinically based, with the following proposed criteria ( Table 3 ) derived from the included studies, in which meeting the criteria (typical presentation) does not require further workup or imaging, unless indicated (e.g., bleeding diathesis). On the other hand, atypical presentation is possible with several related complaints (e.g., abdominal pain or umbilical swelling), which illicit the thought process of different differential diagnoses (e.g., incarcerated hernia, endometriosis, urachal cyst, Sister Mary Joseph nodule secondary to metastatic tumours) ( 9 , 29 ). There is an included case report of a patient presenting with acute abdomen and was diagnosed to have an intrabdominal purulent collection secondary to UPS abscess ( 20 ). It is worth mentioning that UPS may be complicated with abscess formation in 23% of patients (i.e., peri-umbilical swelling, pain and tenderness) which deems it possibly suspicious of other diagnoses (e.g., incarcerated umbilical hernia) ( 6 ). The atypical presentation or suspicion of other differential diagnoses (e.g., incarcerated umbilical hernia), or based on UPS Diagnostic Criteria, the diagnosis is less likely, imaging should be requested, with different available options (e.g., ultrasound, CT abdomen or fistulography, MRI). The radiological choice is dependent on history, examination and availability of imaging. Diagnosis confirmed if both main criterions are present Diagnosis is highly suspected if one main criterion was present with and additional ≥ 1 criterion Diagnosis is less likely if none of the main criterions are present and only additional criteria [other diagnoses must be ruled out] The management of UPS is either conservative (i.e., local debridement and care, regular dressings and possible antibiotics) or surgical with the following techniques: a) Minimally invasive: Umbilicus-preserving sinus excision or modified Gips technique [alternatives: Laser Ablation or Sinus eversion with punch excision and cauterization] b) Umbilectomy (with or without reconstruction). The authors propose a “Step-up” approach in management with initial control of risk factors (e.g., personal hygiene, abdominal laser hair removal, weight-reduction), conservative management, minimally invasive surgical techniques (Laser ablation and Sinus excision techniques) and lastly surgical umbilectomy, starting from the least to most invasive therapeutic measures. Therefore, surgical techniques can be indicated after the failure of management, with “conservative management failure” defined as recurrence of the diagnostic criteria’s confirmation or high suspicion despite ≥ 2 optimal trials of therapy within the past year. The umbilicus preserving sinus excision or modified Gips technique was done in 6 patients with one post-therapeutic recurrence (16.7%) ( 16 , 17 , 20 , 22 , 23 ). The sinus eversion with punch excision and cauterization ( 25 ), and Laser-ablative therapy ( 24 ), were done in one patient each with no recurrence, however these findings cannot be generalizable due to the lack of similar data. Lastly, umbilectomy with or without umbilical reconstruction was done in 134 patients, despite the invasiveness, it has been used directly after conservative management failure, yet in some cases individual-related factors indicate it (i.e., intellectual disability, low socioeconomic status and deep-hairy navels, with inadequate personal hygiene or incapability to follow post-operative dressing follow ups) with the least recurrence (0.7%) ( Figure 3 ). The follow up of patients should be at least for one-year post-intervention, to ensure no recurrence and no further therapeutic measures needed. While emergencies such as abscess formation (i.e., swelling, erythema, tenderness and purulent discharges, other diagnoses must be ruled out via radiological imaging) or intra-abdominal collection ( 20 ), require a different approach (excluded from the discussed approach). Conclusively, our diagnostic criteria and “step-up management”, alongside Ponten et al., algorithm formulate a comprehensive treatment plan for suspected UPS or diagnosed cases ( 29 ). Figure 4 depicts the variety of surgical techniques that were reported, however due to the presence of limited number of patients in all techniques, except umbilectomy, setting a patient selection criteria for each technique was not plausible. The study utilizes a combined technique of a case report and a systematic review, posing a spectrum of controlled (e.g., selection bias) and uncontrolled (e.g., recall bias) biases. The majority of studies had a lack of confounders’ control which leads to a disrupted analysis interpretation, a low sample size or a case report which leads to beta error in inferring associations with unclear management and follow-up protocol. However, assembling a cumulative data pooling lowers the risk of all the, aforementioned biases. In addition, this is the first systematic review targeting UPS related factors, presentation and management; augmenting an evidence-based approach in UPS management, which is deficient in the current available literature.