My daughter was diagnosed with OCD after breaking her arm at her 10th birthday party (shrink said OCD can appear out of nowhere after a trauma) and hers manifested itself in obsession about hair, skin and nails. She thought that if she lost any of those things in public, things that normally slough off your body daily, that someone could find them and trace them back to her, and harm her. It was a real battle for her to leave the house (hysterical crying), and if she finally had no choice, she would wear a hoodie to cover her head, jam her hands in her pockets and wear sneakers in 95 degree Florida heat, so she wouldn't lose skin, hair or nails. Zoloft worked wonders on her; now she is 12 and off the medication, and currently has a slight obsession with germs (lots of hand washing and Purell, which is not necessarily a bad thing--she gets sick about once a year compared to my next door neighbor's kids who are sick literally once or twice a month.)