Concise answer
Jawline acne may be influenced by hormones, friction, shaving, hair or skin products and the usual acne processes of blockage and inflammation. Location alone does not prove a hormonal disorder.
The timing of flares, menstrual or other hormonal symptoms, medicines and product exposure help put the distribution in context.
Deep tender lesions carry a higher scarring risk and should not be repeatedly squeezed.
When evaluation may help
Assessment is useful for persistent, painful or scarring jawline acne, sudden adult onset or acne accompanied by menstrual irregularity or unwanted hair growth.