What is the characteristic appearance of a dermatofibroma?

The characteristic appearance of a dermatofibroma is indeed a firm, raised lesion with a dimpled center. These benign tumors of the skin typically present as small, well-circumscribed nodules that can vary in color from tan to brown. The dimpled center can be observed when the lesion is pinched, which is a classic feature used in clinical differentiation from other skin lesions. The firmness of the dermatofibroma is due to the proliferation of fibroblasts in the dermis, which leads to a fibrous texture.

The other options describe different types of skin lesions. Flat, red patches on the skin are more characteristic of conditions like eczema or psoriasis, whereas soft, movable lumps might suggest lipomas or cysts. Luminous skin with dark spots does not correlate with dermatofibroma presentation and could refer to other dermatological conditions or signs of sun damage. Understanding these distinctions is key in clinical practice when diagnosing skin lesions.