Should I be worried about pimple on scar tissue from breast reduction? (Photo)

The "pimple" you refer to may be a suture abscess. These can be addressed in the surgeon's office and typically heal well once treated. Keep the area clean and dry until you can visit with your surgeon.

Dear dmav,
I understand your concern. It is best that you visit your plastic surgeon for further assessment or ask for a second opinion. Only after a thorough examination, you can get proper recommendations and advice.
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

In the photo submitted it looks as though the area of concern represents a small stitch abscess. Even though it is called an ‘abscess’, a stitch abscess is simply a partially digested suture that has worked its way to the skin surface. When performing surgical procedures such as a tummy tuck or in this case a breast reduction, multiple layers of slowly dissolving sutures are placed under the skin in order to impart strength at the closure site. More often than not, while most of the sutures we place get completely dissolved by the body, there are a couple sutures which will make their way to the skin surface. The appearance is just how it appears in the submitted photos-- like a small pimple. It will often pop, may drain slightly for a day or two, and then heal up quickly without difficulty. I would keep it clean and cover it with a Band-Aid and Neosporin until it resolves. While it is unlikely to represent a larger, underlying infection you will want to monitor for any additional symptoms which may require further interventions such as a wound culture or antibiotics. If you just start to develop symptoms such as fevers, chills, nausea, vomiting or redness that spreads beyond the area you should contact your surgeon immediately to be seen.