What type of lesions are described as initially being pea-sized papules that become vesicular?

The described lesions as initially being pea-sized papules that undergo transformation into vesicular lesions are characteristic of impetigo. Impetigo is a common and highly contagious skin infection that primarily affects children, and it usually begins as small, red bumps or papules on the skin. These papules can evolve into vesicles or blisters filled with fluid, and eventually, they may rupture and form a crust. The evolution from papule to vesicle is a key feature in recognizing impetigo.

In contrast, conditions like abscesses typically feature painful, swollen areas filled with pus, which don't start as papules and usually don't progress through a vesicular stage. Psoriasis usually presents with raised, red patches covered with thick, silvery scales but does not typically exhibit vesiculation. Shingles, caused by the reactivation of the varicella-zoster virus, typically presents with a painful rash that progresses from macules to vesicular lesions, but the initial presentation involves more than just pea-sized papules.

Overall, the progression described in the question aligns well with the clinical presentation of impetigo, making it the correct answer.