Final answer:
Erythema migrans can enlarge to 5 to 65 cm in diameter at the site of a tick bite, which might be associated with Lyme disease. Ticks can be as small as less than 2 mm, making them difficult to spot.
Step-by-step explanation:
Erythema migrans typically presents as an initial papule or macule at the tick bite site and can enlarge over days. The size it reaches can vary, but it is not uncommon for the affected area to become quite large. When associated with Lyme disease, which is a tick-borne illness, the characteristic rash of erythema migrans can expand to be 5 to 65 cm in diameter. These ticks, particularly the nymphs that are less than 2 mm in size, can be easily overlooked due to their small size compared to common objects like a dime. When bitten by such ticks, initial cold-like symptoms with a high fever may present first, followed by the erythema migrans rash three to five days later.