Dx Tinea (corporis) vs Granuloma Annulare

Tinea => border is scaly


Granuloma Annulare => border is non-scaly

Dx Acne Vulgaris vs Acne Rosacea

Vulgaris => comedones (keratin plugs in pilosebaceous unit) - white or black (if oxidised)


Rosacea => no comedones


NB:
Important DDx of (white heads) comedones = Milia  |  Usually found in infra-orbital/cheek regions

Milia = keratin "bleb" vs keratin "plug" in vulgaris (forming a comedone)