Final answer:
The difference between a macule and a patch is primarily their size; macules are flat skin discolorations less than 1 centimeter, while patches are larger, flat, nonpalpable areas of discolored skin greater than 1 centimeter. Characteristics such as symmetry, borders, and color further aid in distinguishing benign from malignant skin lesions.
Step-by-step explanation:
The primary difference between a macule and a patch lies in their size. A macule is a flat discoloration on the skin that is less than 1 centimeter in diameter. It can appear in various colors such as red, brown, or hypopigmented. Conversely, a patch refers to a flat, nonpalpable area of skin discoloration that is larger than 1 centimeter. The color of a patch can also vary, and it may be due to a birthmark, a vitiligo lesion as indicated by Figure 5.10 where individuals experience depigmentation, or a part of a skin condition like melanoma where it typically presents as a large patch with uneven borders and raised surfaces.
Of note, characteristics such as the symmetry, borders, and color can also help differentiate benign from malignant lesions. For instance, the ABCDs of Skin Cancer suggest that a benign mole is generally symmetrical and even in color, whereas a potential skin cancer like melanoma may be asymmetrical, have irregular borders, and exhibit multiple colors or dark pigmentation.
Therefore, while both macules and patches are types of skin lesions characterized by changes in color or pigmentation, the key difference lies in the size, with macules being smaller than 1 centimeter and patches being larger.