Case of constriction band syndrome with annular epidermal cyst.

Both intrinsic and extrinsic theories have been proposed to explain the etiology of congenital constriction band syndrome. The authors report a case of construction band syndrome in which an epidermal cyst was involved. It was located along the annular band of the affected finger and formed a complete ring. This case suggests that the epidermal cyst was produced by circumferential compression, advocating the extrinsic theory for this syndrome.