Hi,
A cystic pimple (often termed acne cyst by doctors) is caused by very intense inflammation resulting in breakdown of tissue where the pimple first started. This broken down tissue is mushy and jelly-like. Understanding this, if you have a cystic pimple, your doctor will attempt to reduce the inflammation fast to give you quick relief as well as to minimize future scarring.
The reduction of intense pimple inflammation often requires oral medication such as antibiotics or isotretinoin. A local injection of a mild steroid solution (e.g. triamcinolone acetonide) will act to quickly reduce the local inflammation and allow the cystic pimple to shrink faster.
A larger cystic pimple (e.g. more than 10mm in diameter) that fails to respond to the above combination treatment may require a minor surgical procedure to extract the pus.
Hope this helps!
