Bilateral inframammary pilonidal sinus: A case report with literature review

Highlights • Sacrococcygeal PNS is the commonest variant of the condition.• However, it can occur in other areas like umbilicus, hand, scalp intermammary, suprapubic, nose, etc.• Infra mammary PNS is an extremely rare condition, with no previous report.• This study aims to present and discuss a case of PNS occurring in both infra mammary regions.


Introduction
PNS is a chronic inflammatory disorder that occurs due to hair involution of epidermis [1]. The most common area is the sacrococcygeal region [2]. It may also occur in rare areas like umbilicus, nose, suprapubic, groin, interdigital web, axilla, clitoris, prepuce and penis [3]. Clinical manifestations are pain, heat and swelling [4]. It is a disease of puberty and adulthood. Male gender is affected more than females by a ratio of 3:1 [5]. Diagnosis of perianal PNS is clinical, however in a case of atypical PNS high index of suspicion is required to suspect the condition [6].
Up to date, 17 cases of intermammary PNS have been reported in the literature, while no inframammary case has been reported [7][8][9][10][11]. This study aims to report a case of bilateral inframammary PNS in line with SCARE guidelines with brief review of intermammary PNS [12].

Patient information
A 25-year-old female presented with multiple discharging sinuses in the both inframammary areas that extends into the intermammary region for two years. Past and family histories were clear. She was non-smoker and single.

Clinical findings
There were multiple discharging sinus extending from left inframammary region, through the intermammary area to the right    inframammary sitewith 8 × 9 cm of induration and tenderness ( Fig. 1).

Therapeutic intervention
After preparation for general anesthesia, complete excision of the sinus tracts was performed through a butterfly shaped incision (Fig. 2). Primary closure was done after irrigating the wound with povidone solution and normal saline. Corrugate drain was placed (Fig. 3). Histopathological examinations showed chronic foreign body granuloma surrounding hair shaft pictures consistent with PNS.

Follow-up and outcomes
Two weeks later, the drain was removed. After six months, the scar was healthy, there was no sign of recurrence.

Discussion
PNS is a suppurative disease that occurs due to hair penetration of epidermis, causing a sequelae of foreign body reaction: inflammation, sinus formation and granulation tissue lined tract [13]. PNS mostly occurs in young people with a male to female ratio of 4:1 [14].
The etiology for PNS was not known until recently (Although the etiology is not well known but nowadays the disease has an acquired etiology) [15]. PNS formation can be attributed to four major reasons: First is penetration of the skin with hair; second, wrinkling of the skin, like in the natal cleft or a scar; third, hormonal and hygienic effects.
The fourth cause is pressure on atypical areas, such as intermammary area by pressure effect of breasts [8,16]. Reports of atypical PNS have increased in the last few decades [16]. A systemic review by Salih et al. found that in more than 300 patients, there are 10 sites for atypical region for PNS to occur other than sacrococcygeal region [16].
In general, the reported risk factors for PNS are hairiness, young age, male gender, prolonged sitting, deep navel and cleft and poor personal hygiene [6]. While the specific risk factors for intermammary PNS is large breast size and tight bra [11]. The current case also reported large breasts and constricting bra.
The differential diagnosis for an atypical PNS is a long list such as hernia, endometriosis, urachal cyst, epidermoid cyst, pyogenic granuloma, dermoid cyst and infected sebaceous cyst [16].
The diagnosis of atypical PNS is not straight forward. Most of intermammary PNS cases can't be diagnosed preoperatively. Shreef et al. reported 12 cases of intermammary PNS, where only 25% of the cases could be diagnosed preoperatively [11]. In the current case, PNS was suspected preoperatively because of high prevalence of atypical PNS in our locality [1].
There is no standard strategy for management of PNS. It varies from extensive resection to conservative therapy. Injection of a mixture (100 g petroleum jelly (Vaseline) +50 g henna powder (Lawsoniainermis powder) +5 g tetracycline, that was stored at 2 • C-8 • C.) to the PNS site had an extraordinary effect on the patients; they returned to work immediately compared with the operative groups, who stayed at home for at least 10 days [17]. Management of umbilical PNS mostly involves removal of hair and daily dressing without anesthesia, but umbilectomy has been done under general anesthesia [1]. Up to ninety percent of interdigital and hand PNS were treated by surgical excision under general anesthesia [13]. Scalp PNS were treated by excision but one patient required craniotomy [3].
Definite therapeutic approach of intermammary PNS is excision and primary closure [7][8][9][10][11]. The current case was managed by wide local excision with primary repair under general anesthesia.
In conclusion, pilonidal sinus of inframammary area is an extremely rare condition. It is mostly associated with obesity and large breasts with tight brassieres. As intermammary PNS, excision with primary closure is the definitive therapy.

Sources of funding
No source to be stated.

Ethical approval
Approval is not necessary for case report in our locality.

Consent
Consent has been taken from the patient and the family of the patient.

Registration of research studies
Not applicable.

Provenance and peer review
Not commissioned, externally peer-reviewed.

Declaration of Competing Interest
There is no conflict to be declared.