Definition from Wiktionary, the free dictionary
Blend of back + acne
bacne (plural bacnes)
- (informal) Acne on the back.
- Bacne seems to be suffered more by men than by women, though women do have outbreaks of acne on their backs as well. - Acne Resource Center
- The bacne regimen is identical to the regular regimen with the addition of an 8-10% glycolic acid (alpha hydroxy) lotion. - Acne.org