Axillary pilonidal sinus: A case report.

CONTEXT: Pilonidal sinus is a disease which is very common, especially in men and usually located in sacrococcygeal area. However, the disease can be also seen in rare localizations such as umblicus, forehead, scalp, clitoris, interdigital area and axilla. In the etiology of pilonidal sinus, acquired theory is accepted by most of surgeons instead of the congenital one. CASE REPORT: In the present study, we purposed to report our case of hirsute Turkish women aged 25 having axillary pilonidal sinus. After application of total surgical excision with eliptical skin incision, histopathological evaluations confirmed the prediagnosis of axillary pilonidal sinus. The patient was lost to follow-up and neither recurrens nor distance metastasis has been detected during 36 months.
CONCLUSIONS: In our opinion; surgical therapy of axillary pilonidal sinus, allows to complete resection in addition to absolute histopathological diagnoses and it may be an appropriate choice of treatment especially for the disease having one or two sinuses.

Introduction

Pilonidal sinus is a disease which is reported by Anderson et al[1] as a hair detected in a sacrococcygeal ulcer in 1847, defined firstly by Hodges et al[2] as a term of pilonidal sinus and mostly found in sacrococcygeal area[34]. Besides this area, it can be also seen in rare localizations such as umblicus[5], forehead[6], scalp[7], clitoris[8], interdigital area[9], penis, abdomen, neck and axilla[10-1213].

In the etiology of pilonidal sinus, congenital theory was accused by Kooistra et al[3] in 1942, collection of hairs on midline of back was become a current issue by Karydakis et al[14] firstly in 1992 and acquired theory was reported by Bascom et al[15] in 1980.

Case Report

A hirsute Turkish woman aged 25 applied to our clinic in November 2006 with the history and complaint of the intermittent small amount of leakage from her right axilla during the past year. There was no any history of pilonidal sinus and operation of which at the other sites of her body.

On the physical examination, one small sinus sized 2 mm in diameter in her right axilla not including any hair was detected. No discharge was observed in inspection and also palpation. The edematous area of 1 cm in length was recognized around the sinus. Pilonidal sinus was defined at neither the intergluteal sulcus and nor the other regions of her body.

The surgical treatment was performed via eliptic skin incision. After application of methylene blue through the orifice of the pilonidal sinus, total excision of the tractus with the neighbouring subcutaneous tissue and the elliptical skin part containing the sinus orifice was performed. Following the total surgical excision, primer suturation of the subcutaneous tissue and the skin were carried out. The tractus was limited only in subcutaneous tissue and the histopathological evaluations confirmed the preassumptive diagnosis of axillary pilonidal sinus. Any perioperative or postoperative complication and recurrence has not been detected during the 36 months follow-up.

Sinus tract and the section of the hair inside it (arrows) (H & E, original magnification, 10×20).

Apocrine gland structures (thick and short arrows) and the neighbouring section of the hair (thin ang long arrow) (H & E, original magnification, 5×10).

Discussion

In the beginning, the congenital theories have been suggested for the pathogenesis of pilonidal sinus, but afterwards the acquired theory is accepted by most of surgeons[4-16]. Friction (abduction – adduction), suction, massage, shaving, pounding, minor infection and maceration are assorted mechanisms which play a part in acquised theory of pilonidal sinus[16].

Mayo et al[5] indicated that the hairs may curl back on themselves and pierces the surrounding skin with their distal ends first by growth forces. On the contrary, Oryu et al[10] suggested that penetration of shed hairs with their proximal or distal ends first coul not be designated, so the mentioned authors could not be designate the penetration direction of hair in their 5 patients.

We come accross with axilla as a very rare body area for including pilonidal sinus[10-1216]. Differential diagnosis of axillary pilonidal sinus consist of folliculitis and ruptured epidermal cyst[16]. Malignant degeneration of pilonidal disease is a rare complication composed of approximately 0.1 % of patients with chronic untreated or recurrent pilonidal disease[1718] and is associated with a high recurrence rate and poor prognosis comparing with regular nonmelanoma skin cancer. Among malignant degeneration of pilonidal sinus most cases are squamous cell carcinoma[19]. Biological behavior of pilonidal sinus carcinoma is much more aggressive than squamous cell carcinoma at the other sites[17] and they are deeply invasive into the subcutaneous tissue in the great majority of cases. Underlying bone is involved in 8% of cases, also. I nguinal lymph node metastasis is very poor as a prognostic sign and is associated with a median survival time of only 7 months[20].

According to our point of view, besides complete resection allows to appropriate choice of treatment especially for the disease having one or two sinuses[16], it also enables to absolute histopathological diagnoses.

In conclusion, pilonidal disease is a very common disease, especially in men and generally located in sacrococcygeal area. However, axillary pilonidal sinus is very rare. So, we aimed to present our case of hirsute young Turkish women having the mentioned disease. Histopathological evaluations revealed the charecteristic structures of axillary pilonidal sinus, after application of total surgical excision via eliptical skin incision. The case was lost to follow-up and no recurrens or complication has been detected during 36 months. Awareness of the probability of a pilonidal disease even in seldom locations like groins of axilla is important and although the malignant degeneration of the disease is very rare, it has much more poor prognosis comparing with squamous cell carcinoma and regular nonmelanoma skin cancer.