A small, raised bump of skin beside a baby boy's anus turned out to be the only visible part of something far stranger. Beneath it, doctors in Japan found a slender stalk of tissue that ran deep into the fat beside the rectum and ended in a nodule of joint-type cartilage and bone marrow.
Altogether, the dumbbell-shaped structure measured about 7 centimeters. Its makeup resembled tissue described in rare human tails, except that it never broke the surface. The team reported the case in Case Reports in Pathology, with the paper published online in July. The authors wrote that, to their knowledge, no similar cases have been reported.
