A different disease: extrasacrococcygeal pilonidal sinuses etiopathogenesis.

Pilonidal sinuses (PS) predominantly affect young male adults, usually occurring in the sacrococcygeal region. However, PS occasionally occurs in other parts of the body, referred to as extrasacrococcygeal pilonidal sinus (ESPS). We herein evaluate ESPS ethiopathogenesis and treatment. Of a total of 949 PS cases treated between 2006 and 2011, 21 were of ESPS (2.2% of the total), which were evaluated retrospectively. The affected regions were the breast (n = 1), scalp (n = 2), sternum (n = 2), abdominal wall (n = 5), neck (n = 2), groin (n = 4), and axilla (n = 5). Lesions of the abdominal wall are rare, but less so than lesions in other regions. PS may mimic hidradenitis suppurativa histologically. To our knowledge, PS of the breast and groin have not previously been reported. Twelve of our patients reported shaving the affected region; we suggest this may have played a role in the disease pathogenesis.