A steatoma is defined as what?

A steatoma is accurately defined as a fatty deposit within a sebaceous gland. These benign cystic lesions, often referred to as sebaceous cysts, form when there is a blockage in the gland, leading to an accumulation of sebum, the natural oil produced by the skin. The presence of this excess oil causes the characteristic lump or cyst, typically appearing on the scalp, neck, or back, although they can develop anywhere on the body.

The other options do not capture the specific nature of a steatoma. For instance, while an excess of oil can lead to various skin issues, it doesn't specifically define a steatoma. Similarly, a herpes outbreak is related to viral infections affecting the skin and mucous membranes and does not relate to fatty deposits. An allergic reaction involves the immune system responding to a substance, which is entirely different from the formation of a steatoma. Thus, option B provides the precise definition consistent with established dermatological terminology.