Pilonidal sinus of the umbilicus.

Only 15 cases of pilonidal sinus of the umbilicus have so far been reported. A 16th case is described; it supports the theory of acquired origin of the disease. The case fulfilled the criterion for pilonidal sinus--the 36-year-old man had a hair in the infected umbilical cyst. The cyst and umbilicus were excised. The umbilicus was not reconstructed because of the danger of recurrence. It is recommended that a careful search be carried out for hair in all patients with an infected umbilicus.