What is a common feature of sebaceous cysts?

A common feature of sebaceous cysts is the presence of a firm, round lump beneath the skin. These cysts are generally characterized by their encapsulated nature, containing keratin and other cellular debris. They usually present as well-defined, firm, and movable masses located just under the skin. This distinctive texture and shape help differentiate sebaceous cysts from other types of lesions or skin conditions that may present differently.

In contrast, options that describe an itchy, inflamed rash or dyspigmented patches are more indicative of conditions such as eczema or vitiligo, which have different underlying etiologies and presentations. Ulcerated lesions suggest a breakdown in the skin barrier, which is not typical for a sebaceous cyst, as they do not usually become ulcerated unless there is infection or trauma. Thus, the defining characteristic of sebaceous cysts as a firm, round lump under the skin is paramount in identifying them accurately.