Final answer:
A solid mass in the skin that may be elevated or deep, soft, or hard, fixed or freely movable is correctly termed a nodule. It is important to distinguish this from other types of skin lesions like pustules, papules, and vesicles, since each indicates different underlying conditions and requires specific treatments.
Step-by-step explanation:
A solid mass in the skin that may be elevated or deep, soft, or hard, fixed or freely movable is called a nodule. This type of skin lesion can vary in size but is typically larger than a few millimeters in diameter. A nodule can be associated with a variety of conditions, ranging from acne, which often presents as inflammatory lesions such as pustules, to more serious conditions like tuberculoid leprosy, which could cause lesions and pustules that would contain the microorganism responsible for the disease.
Other types of skin lesions include papules, which are small raised bumps on the skin; vesicles, which are fluid- or pus-filled bumps; and pustules, which are pus-producing lesions. It's important to differentiate among these when diagnosing skin conditions, as their characteristics and underlying causes can vary significantly.