Russell's sign

Russell's sign is a sign defined as scarring on the knuckles or back of the hand due to self-induced vomiting over long periods of time. The condition generally arises from the afflicted making contact with the incisor teeth during the act of inducing the gag reflex at the back of the throat with their finger(s).

This type of scarring is considered one of the physical indicators of a mental illness, and Russell's sign is primarily found in patients with an eating disorder such as bulimia nervosa or anorexia nervosa. However, it is not always a reliable indicator of an eating disorder. Russell's sign may be dermatologically treated with urea.

Bulimics who are capable of "handsfree purging", or the induction of vomiting by willful opening of the lower throat flapper (esophageal sphincter) in a manner similar to when belching, while contracting the stomache muscles, rarely have Russell's sign. This is primarily true since handsfree bulimics do not need to thrust their hands down their throats in order to release consumed food, and thus, do not harm their hands during the act of purging.

References

* Tyler I, Birmingham CL. The interrater reliability of physical signs in patients with eating disorders. Int J Eat Disord. 2001 Nov;30(3):343-5. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11767717&dopt=Abstract PMID: 11767717] .
* Strumia R. Dermatologic signs in patients with eating disorders. Am J Clin Dermatol. 2005;6(3):165-73. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15943493&query_hl=8 PMID: 15943493] .