Early sonographic detection of a 'human tail': a case report

We report on a newborn in whom an echogenic protrusion arising in the cauda l region was detected at 12 weeks' gestation. Subsequent ultrasound examina tions at weeks 15 and 22 failed to demonstrate this finding. After birth, t he infant was found to have a pilonidal sinus. The pilonidal sinus may repr esent a remnant of the embryonic appendage (human tail') that usually disap pears by the end of the 8th week of gestation. This case might support the theory of congenital pilonidal sinus origin.