Abstract
We report a case of pilonidal sinus on the umbilicus. A 35-year-old man was seen at the hospital on referral from his family doctor because of umbilical exudates and subcutaneous induration for three months. The doctor suspected urachal remnant. Abdominal computed tomography showed an enhanced high-density area corresponding with the umbilical fossa, but no positive findings of urachal remnant. The umbilicus was covered with hard hair. We made an incision into the subcutaneous induration under spinal anesthesia, and found a granulomatous pouch filled with hair. This finding allowed us to diagnose pilonidal sinus on the umbilicus. Pilonidal sinus on the umbilicus has been reported in 6 cases, including this case, so far in Japan. Surgical resection is proposed as the definitive treatment, because the hair causes inflammation.
