These are two entirely different entities. An epidermal inclusion cyst ( sometimes referred to as a follicular cyst) is caused when there is irritation to the follicle opening. This causes cells to proliferate and the opening becomes clogged. The keratin which normally fills the follicle and is emitted to smooth the skin, cannot escape and begins to pile up, ballooning out the follicle wall. Sometimes, these are referred to as a "sebaceous cyst". This is a misnomer for a number of reasons: 1) the contents are keratin and not sebum 2) the cyst cavity is lined by squamous epithelium and not sebaceous glands 3) sebaceous glands are usually squeezed so much by the cyst that they cannot even be found and 4) there is a growth called a steatocystoma multiplex which IS a sebaceous cyst.
Anyway, most physicians can tell the difference between the two. By palpation ( feeling) the sebaceous cyst will feel a bit firmer than the lipoma, it is also usually more round. Upon observation, one can see a small hole ( punctum). These is the center of the cyst where the pore was originally clogged.
A lipoma consists of benign fatty tissue. Small lipomas can be easily removed in physician's office as they usually pop out. If the lipoma is tender, this is usually an angiolipoma. A fatty tumor with increased blood vessels running through them.
Neither of these are dangerous or can cause death. Though an epidermal inclusion cyst may have cancer in it on very rare occasions ( have seen this twice in 32 years), the type is often quite non-aggressive.
Both lipomas and epidermal inclusion cysts can be removed with minimal blood loss
