Diagnostic criteria

Simplified classification [5]

• Mild: comedones are the main lesions. Papules and pustules may be present but are small and few in number (generally <10).

• Moderate: moderate numbers (10 to 40) of papules and pustules. Moderate numbers (10 to 40) of comedones are also present. Sometimes mild truncal disease.

• Moderately severe: numerous papules and pustules (40 to 100), usually with many comedones (40 to 100) and the occasional (up to 5) larger, deeper nodular inflamed lesions. Widespread affected areas usually involving face, chest, and back.

• Very severe: nodulocystic acne and acne conglobata with severe lesions; many large, painful nodular/pustular lesions along with many smaller papules, pustules, and comedones.

FDA global grade [31]

Used primarily for research purposes.

• Grade 0: clear skin with no inflammatory or non-inflammatory lesions

• Grade 1: almost clear; rare non-inflammatory lesions with no more than 1 small inflammatory lesion

• Grade 2: mild severity; greater than grade 1; some non-inflammatory lesions with no more than a few inflammatory lesions (papules/pustules only, no nodular lesions)

• Grade 3: moderate severity; greater than grade 2; up to many non-inflammatory lesions and may have some inflammatory lesions, but no more than 1 small nodular lesion

• Grade 4: severe; greater than grade 3; up to many non-inflammatory and inflammatory lesions, but no more than a few nodular lesions.