Introduction

Pilonidal sinus of the umbilicus, though a rare occurrence, should be considered in the differential diagnoses of an umbilical nodule as a simple extraction of the hair will relieve the symptoms in most of the cases.₁

Case Report

A 24-year-old male presented with a three-year history of a painful umbilical swelling with reddish discharge. There was no history of trauma, fever or vomiting. Clinically, a diagnosis of umbilical adenoma was entertained. The swelling was excised and sent for histopathological examination.

Pathological findings

The specimen received was a skin-covered tissue with attached hair, measuring 2.5 x 4 x 1.5cm. Cut section showed a fistulous tract containing hair with firm grey-white areas.

Microscopic biopsy sections showed squamous epithelium overlying a fistulous tract lined by granulation tissue and chronic inflammatory cells containing hair shafts consistent with umbilical pilonidal sinus. (Fig. 1 & 2)

Figure 1

Fig 1: Sinus with hair shaft surrounded by lymphoplasmacytic infiltrate

Figure 2

Fig 2: Sinus containing hair shaft

Discussion

Pilonidal sinus commonly occurs in the sacral region and involvement of the umbilicus is a rarity, with only few cases being documented in the literature. Patey and Williams documented the first case of umbilical pilonidal sinus in 1956.₁ It is caused by hair penetrating the skin, resulting in a foreign body reaction and development of a sinus lined by granulation tissue. The patient may be asymptomatic initially or present with pain, discharge or bleeding from the swelling.₂ Male sex, young age, heavy hirsutism, deep navel and poor personal hygiene are the most common predisposing factors.₃ Umbilical pilonidal sinus carries a risk of peritoneal extension of inflammation, therefore, it should be included in the differential diagnosis of umbilical nodules and treated more aggressively than its sacrococcygeal counterpart.₄ The major differential diagnoses for umbilical pilonidal sinus include umbilical adenoma, umbilical hernia, endometriosis, metastatic tumor and congenital abnormality which can be distinguished on histopathology.₁

A conservative management is recommended by many authors for umbilical pilonidal sinus. Surgical treatment is restricted to recurrent cases resistant to conservative treatment.₃

Conclusion

Though umbilical adenoma, umbilical hernia, congenital abnormalities and endometriosis are more common conditions leading to an umbilical nodule, pilonidal sinus should be considered, as a simple extraction of hair in this case will relieve the symptoms in most patients.