Erythema Multiforme: This condition is characterized by target lesions (erythematous papules with a white or pale center) and is often associated with infections (especially herpes simplex) or medications. The description provided closely matches the classic presentation of erythema multiforme.

Urticaria: Although urticaria (hives) typically presents with wheals that are pruritic and transient, some forms can have a more persistent and erythematous appearance, potentially resembling a papular rash with central clearing.
Pityriasis Rosea: This condition starts with a herald patch, followed by a widespread, symmetrical eruption of pale pink, scaly patches, often with a characteristic "collarette" scale at the edge, which might be confused with a white center in some cases.
Tinea Corporis (Ringworm): While typically presenting with annular lesions having a clear center, the early stages or certain variants might appear as erythematous papules with a white center, especially if the scale is minimal or not readily apparent.

Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis (SJS/TEN): These are severe skin conditions usually triggered by medications or infections, characterized by widespread skin necrosis and detachment. Early stages might resemble erythema multiforme but with more severe systemic symptoms and rapid progression. Missing this diagnosis could be fatal.
Rocky Mountain Spotted Fever (RMSF): An infectious disease caused by Rickettsia rickettsii, transmitted by ticks. It presents with fever, headache, and a characteristic rash that can start as erythematous papules and may have a white center, progressing to petechiae. Delayed treatment can lead to severe complications.

Sweet Syndrome (Acute Febrile Neutrophilic Dermatosis): Characterized by the sudden onset of fever, leukocytosis, and tender, erythematous, well-demarcated papules and plaques, which might resemble the described rash. It's often associated with underlying conditions like infections, inflammatory bowel disease, or malignancies.
Erythema Marginatum: A rare condition associated with acute rheumatic fever, presenting as evanescent, pink rings or annular lesions that might be confused with a rash having a white center due to their pale, central areas.