What is characterized by lesions that start as 1-2mm central yellowish papules surrounded by halos in newborns?

The condition characterized by lesions that begin as 1-2 mm central yellowish papules surrounded by halos in newborns is erythema toxicum. This common neonatal rash typically presents within the first few days of life and appears as multiple small, raised bumps that can have a yellowish center with an erythematous halo around them.

Erythema toxicum is a benign and self-limiting condition, generally resolving on its own within a few days to weeks without treatment. It is thought to be related to the newborn's adjustment to the external environment and the maturation of the immune system. The characteristic appearance of the lesions, along with their typical onset and self-resolving nature, makes erythema toxicum the correct answer in this scenario.

Other conditions mentioned have distinct presentations; for example, strawberry hemangiomas are raised vascular lesions that appear as red or purple spots, often growing before regressing over time, while herpes simplex presents with vesicular lesions that are painful and commonly associated with systemic symptoms. Additionally, sternocleidmastoid issues relate to muscular abnormalities and do not involve skin lesions similar to those described.