Oil Cyst or Fat necrosis

A 34 years old female Patient that complains of breast lump and a history of breast trauma. Diagnosis was of an oil cyst.
Note............egg-shell calcification.

So,What is oil cyst ?!
Oil cyst that also called Fat necrosis occurs when there is saponification of local fat, usually after a direct trauma. Middle-aged women with pendulous breasts are Most at risk.

At first, they are ill-defined and irregular spiculated dense masses. However, with time, they become more defined and well-circumscribed. The centre of the lesion becomes increasingly with homogenous with fat-density.