This is a very good question as lumps are a very common problem encountered in general practice.
You should consult your family doctor to perform an initial history taking and physical examination to better understand how serious/suspicious the lump is.
The purpose of the a physical examination on a lump is to determine if the lump had grown out from the skin layer or deeper layers of the chest (aka where the likely origin of the lump is).
The majority of lumps that are felt by patients arises from the skin or its deeper layers (medically called the subcutaneous tissue). These lumps feel soft and are not fixated to the bone.
For the chest, lumps can also arise from the deeper layers such as the muscle or even the ribs. For a female, it is also important to ensure that the lumps do not come from the breast tissue (a breast lump closer to the middle of the chest can also mimick a skin lump).
Having a lump can be very worrying as most people are concerned that it is cancerous. The good news is that majority of these lumps are non cancerous. There are however, certain features such as skin erosions and rapidly increasing in size and shape of lump that makes a lump suspicious for cancer.
Based on how large/superficial/suspicious the lump appears, I routinely refer my patients with lumps in the chest to either to a general surgeon/thoracic surgeon or a dermatologist if the lump is very superficial.
If a lump feels benign and is relatively small and superficial, your doctor may suggest for an excision (medical word for cutting out) of the lump. If they suspect it is large or may involve deeper layers of the muscle and bone, they may need to order investigations such as an ultrasound or even a CT/MRI scan to better determine what we are dealing with before suggesting the best technique to resolve the lump.
