Intermamarian plinodial sinus is a rare location: how well do we know it in primary care?

Authors

Abstract

AimIn the present study, we aimed to assess the clinical complaints, possible etiologies, treatment processes, and recurrence statuses of patients who presented to our clinic with a preliminary diagnosis of intermammary pilonidal sinus disease (IMPSD) and were treated.
MethodsPatient files of those who underwent surgery for IMPSD at our clinic were retrospectively evaluated. This retrospective clinical review collected data through the hospital automation system. Data were analyzed using Statistical Package for the Social Sciences 23.0 software.
ResultsA review of patients’ medical histories showed that 9 (69.2%) patients presented to family medicine outpatient clinics due to their complaints. Six patients were referred directly to the dermatology outpatient clinic after examination. Three patients were prescribed medical treatment in addition to antibiotics and referred to the dermatology outpatient clinic after their complaints did not improve during the follow-up examination. In etiology, having large breasts and wearing a tight bra are significant factors.
ConclusionOur research findings indicate that family physicians lack knowledge about recognizing IMPSD and that awareness and training activities are essential in family medicine. IMPSD should be considered in patients with redness and discharge in the intermammary gland area.

Keywords

Introduction

Pilonidal sinus disease (PSD) is a chronic inflammatory disease of the skin and subcutaneous tissue that occurs as a result of hair penetrating the epidermis. It is usually characterized by the presence of pilonidal cysts, discharging sinuses, and abscesses.¹ Although it is most commonly observed in the sacrococcygeal region, intermammary pilonidal sinus disease (IMPSD) is an extremely rare variant that occurs in the intermammary sulcus. Few IMPSD cases have been reported in the literature; however, available data show that this condition primarily affects young women.² This disease usually occurs between the ages of 18 and 40. Most cases in the literature have been reported from Türkiye, Iraq, and India.³
Whereas general risk factors for PSD involve hirsutism, a sedentary lifestyle, and obesity, specific risk factors for IMPSD include having large, sagging breasts and wearing a tight bra.^4,5 Tight bras create a deep groove, similar to the intergluteal region, suitable for hair entry. IMPSD patients are overweight or obese. Furthermore, about 24% of IMPSD cases have been reported to have comorbidities, such as polycystic ovary syndrome (PCOS).⁶ Pathophysiology focuses on the acquired nature of the disease; the basic mechanism is the implantation of hairs beneath the dermis in regions exposed to high pressure and friction, and the other mechanism is the initiation of ingrowth and inflammation due to blockage of hair follicles by microbial agents or skin debris.⁷
Clinically, the diagnosis of IMPSD is mainly based on clinical assessment, and additional imaging studies are rarely needed. The disease can display a wide range of symptoms, from asymptomatic to acute abscesses or chronic discharging sinuses.⁸ Most cases present with discharging sinuses (66.66%) and painful swelling. The mean duration of symptom onset of 8.4 months indicates the condition’s chronic nature.⁹ Since there are no standard treatment guidelines due to the rare occurrence of the disease, an individualized management plan is required. While incision and drainage are applied for acute abscesses, surgical excision is the main treatment for chronic disease. Since there is loose skin in the intermammary region, the primary closure technique after excision causes fewer technical problems, ensures faster healing, and is frequently preferred. The recurrence rates have been reported to be 7.14%.⁹ Flap techniques, such as shifting the incision site from the midline, have also been employed to lower the risk of recurrence.
In the present study, we aimed to assess the clinical complaints, possible etiologies, treatment processes, and recurrence statuses of patients who presented to our clinic with a preliminary diagnosis of IMPSD and were treated.

Materials and Methods

The current study involved patients who presented to our hospital's general surgery outpatient clinic between January 2015 and July 2024 with complaints of discharge, redness, or pain in the intermammary region. Patients’ files were examined retrospectively. The study included patients who underwent surgery and were diagnosed with PSD based on the postoperative histopathological examination. Patients' age, sex, body mass index (BMI), medical history, comorbidities, surgical procedure, and recurrence status were assessed. Patients whose files could not be accessed, who had incomplete information, who did not attend follow-ups, or who were not histopathologically diagnosed with pilonidal sinus disease were not included in the study.
TechniqueAll patients underwent a surgical procedure using the same technique. Informed consent was obtained prior to surgery. All procedures were carried out under laryngeal mask anesthesia. Before the incision, surgical margins were identified by injecting methylene blue into the sinus openings. An elliptical incision was made to include the sinus openings (Figure 1). An excision was performed, extending to the fascia at the sinus floor. Flaps were prepared from the fascia using cautery, and the incision was shifted from the midline. The skin incision was closed subcutaneously using absorbable Vicryl sutures (Figure 2). Drains were placed in patients with a large excision site. The specimens were sent for pathological examination.
Ethical ApprovalThis study was approved by the Ethics Committee of Atatürk University, Faculty of Medicine (Date: 02.05.2023, Decision No: 3/62).
Statistical AnalysisStatistical analysis was conducted using Statistical Package for the Social Sciences 23.0 (IBM Corp., Armonk, NY, USA). Chi-square tests were used to evaluate categorical variables, while t-tests were used for continuous variables. In addition, multivariable logistic regression analysis was performed to identify independent predictors while adjusting for potential confounders. A p-value of <0.05 was considered statistically significant.
Reporting GuidelinesThis retrospective observational study was reported in accordance with the STROBE reporting guidelines.

Results

A total of 17 patients were assessed, and 13 patients meeting the criteria were included in the study. All patients were female, and their mean age was 22.1 ± 13.4 years (15-66). Patients’ mean BMI was 30.1 ± 2.4 kg/m2. Seven patients were obese (BMI of 30 kg/m2 and above), one patient had epilepsy, and one patient had celiac disease. Three patients had previously given birth and had breastfed for a minimum of two years. Twelve patients stated that they wore tight bras due to a large breast size, and none had hair in the intermammary region. Sinuses were not detected on sacrococcygeal examination in any of the patients. The detailed data are provided in Supplementary Table 1.
Sinus discharge was the most common presenting complaint among patients (n = 11, 84.6%). The mean duration from symptom onset to surgery was 7.6 months. Abscess drainage had been previously applied to 6 patients. All patients had a history of antibiotic use. Imaging for diagnostic purposes was not required in any of the patients.
All patients underwent an excision with an elliptical incision to include the sinus openings. The diagnosis of pilonidal sinus was confirmed on histopathological examination. The mean follow-up duration was 47.1 ± 19.7 months. Seromas not requiring re-surgery developed in the postoperative period in two patients who did not use drains. No recurrence was observed in any patient.
A review of patients’ medical histories showed that 9 (69.2%) patients presented to family medicine outpatient clinics due to their complaints. Six patients were referred directly to the dermatology outpatient clinic after examination. Three patients were prescribed medical treatment in addition to antibiotics and referred to the dermatology outpatient clinic after their complaints did not improve during the follow-up examination. It was found that all patients referred to the dermatology outpatient clinic were also consulted at the general surgery outpatient clinic for further assessment. Two patients presented to the general surgery outpatient clinic on their own, and the other two were referred to the general surgery clinic after abscess drainage was performed in the emergency room.

Discussion

Pilonidal sinus (PNS) is a condition that occurs in the natal (intergluteal) cleft due to acute or chronic infection of the subcutaneous fat tissue.⁸ It primarily occurs as a result of a granulomatous inflammatory process triggered by the irritation of the hair shaft trapped between the epidermis and dermis, causing foreign body reactions and multifactorial infection.¹⁰ The incidence of PNS has increased substantially for unknown reasons.¹¹ Although PNS is observed most commonly in the sacrococcygeal region, it has also been reported less frequently in other regions, including the groin, interdigital pouch, umbilicus, nose, intermammary region, suprapubic area, clitoris, foreskin, penis, occiput, and feet.¹²
Pilonidal sinus disease can present clinically as a silent sinus, acute abscess, chronic sinus infection, or recurrence. Persistent PNS is defined as a history of at least one abscess drainage or persistent chronic discharge without an abscess. It occurs most frequently in the sacrococcygeal region and much less frequently in the intermammary region.¹³ It is thought that intermammary and sacrococcygeal PNS share the same pathogenic processes. Repetitive microtrauma and traction on the urachus lead to the formation of pits, triggering inflammatory and foreign body reactions in the hair shafts, which result in the exposure of the subcutaneous space. ¹⁴
Previous studies have reported that PSD occurs in 67% of males; however, no literature data have indicated that intermammary PSD occurs in males.¹⁵ All patients included in our study were female, which can be attributed to the presence of breasts in females. PSD with both typical and atypical localization is a disease of young individuals aged between 15 and 30.¹² IMPSD occurs in a similar age range to other PSD types. The patients included in our study were in the age range from 15 to 66 years, with a mean age of 22.1 years.
The literature has reported hirsutism as a risk factor for PSM. Different opinions are available in the literature regarding hirsutism as a risk factor for IMPSD.^16,17 None of the patients in the present study had increased hair growth in the intermammary region. Well-known risk factors for IMPSD in the literature include obesity and wearing a tight bra.² Similar to the literature, all except one patient in our study reported wearing tight bras for esthetic purposes, and their BMI varied between 24.3 and 33.7 kg/m2, with a mean BMI value of 30.1 kg/m2. Tight bras can increase hair penetration into the skin by increasing pressure on the intermammary area. Additionally, PCOS has been reported in 24% of IMPSD cases, and hirsutism in 70-80%.¹⁸ Unlike the literature, none of our patients were diagnosed with PCOS or hirsutism. One patient in our study had celiac disease, and one had epilepsy.
Although IMPSD patients may be asymptomatic, 66% of cases present to the hospital with complaints of discharging sinus and 28% with painful swelling.⁹ Patients may have a history of previous abscess drainage. Of the patients in the current study, 84.6% (n: 11) presented to the hospital with discharge, 69.2% (n: 9) with redness, and 53.8% (n: 7) with pain. Seven patients had previously undergone abscess drainage, and all had a history of antibiotic use. All patients with PSD localized in the sacrococcygeal region or with atypical localization have similar clinical symptoms due to the nature of the disease.
No additional imaging is needed to establish the diagnosis of IMPSD. It can be diagnosed based on clinical findings.¹⁷ Ultrasonography (USG) or magnetic resonance imaging (MRI) may be performed in very complicated cases to assist with the surgical procedure.
Surgery is the treatment method preferred in IMPSD. The total excision of cysts is the primary treatment method. Following excision, the site can be managed with primary closure, secondary healing, or curettage. In case of a wide defect area, flap techniques can be employed, as in sacrococcygeal PSD.^4,19 Postoperative recurrence rates in the literature vary between 0% and 25%.^1,5 In the present study, we performed excision with an elliptical incision to include the sinus openings, as we do in our clinic. Thus, we completely excised the pilonidal cysts and shifted the incision from the midline. Owing to this, we detected no recurrence in any of our patients during a mean follow-up period of 47.1 months.
The data from the current study show that a significant part of patients initially presented to family medicine outpatient clinics, but the diagnosis could not be established during this period. Additionally, approximately 8 months passed from the disease onset to diagnosis. The failure to establish the diagnosis at the family medicine level and the long time from disease onset to diagnosis suggest that the relevant disease poses challenges for recognizing clinical findings due to its atypical localization outside the sacrococcygeal region. This indicates that family physicians may have limited awareness and knowledge of IMPSD. Delays in early diagnosis and referral have led to prolonged treatment and repeated visits to different outpatient clinics. Hence, it is thought that planning educational and awareness activities for family physicians to facilitate the recognition of the clinical characteristics of this disease will support appropriate referral and treatment processes.

Limitations

Our study has several limitations. One is that potential causes are assessed based on patient reports as contributing factors. Another limitation is that our study is single-center, retrospective, and has a small number of patients, which may restrict its overall resolution.

Conclusion

Consequently, IMPSD is a condition that should be kept in mind if patients with large breasts and wearing tight bras complain of redness and discharge in the intermammary region. The results of our research indicate that family physicians lack knowledge in recognizing IMPSD and that awareness and educational activities in family medicine are essential. It is necessary to refer these patients to general surgery clinics, their sinus openings should be carefully examined, and appropriate incisions should be made to include all openings. Excision involving the sinus openings and midline shift prevented the risk of recurrence in our patients.

Declarations

Abbreviations

BMI: body mass index
IMPSD: intermammary pilonidal sinus disease
MRI: magnetic resonance imaging
PCOS: polycystic ovary syndrome
PNS: pilonidal sinus
PSD: pilonidal sinus disease
STROBE: strengthening the reporting of observational studies in epidemiology
USG: ultrasonography

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About This Article

Received:

March 13, 2026

Accepted:

April 14, 2026

Published Online:

April 14, 2026