Both epidermoid and pilar cysts are smooth round lumps which you can see and feel just beneath the skin surface. They are very common. Often they are small (pea size) but sometimes they slowly get bigger over many months to become a few centimetres in diameter. They look very similar to each other but can be distinguished from each other if the cells that form the cyst sac are looked at under the microscope.
Acquired Epidermoid Cysts of the Cauda Equina after lumbar puncture - hypodense in T1 and hyperdense in T2. T1 C+ (Gd): no enhancement or a thin rim of capsular enhancement DWI: bright (with corresponding low intensity on ADC map) - Signal intensity may be homogeneous or heterogeneous according to the variable water, lipid and protein composition of the cyst.
There are many types of skin cysts; the most prevalent are epidermoid, pilar or sebaceous, which may become problematic if they get infected. http://articles.mercola.com/sites/articles/archive/2016/08/29/sebaceous-skin-cyst.aspx
Do You Have A Lump On Your Face, Neck, Back Or Behind The Ear? Here's What You Need To Know About Epidermoid Cysts And How To Treat Them