Acne is a term used for plugged pores, pimples, deep lumps (nodules or cysts) that generally occur on neck, face, back, shoulders, chest or even on the upper arms. Generally, teenagers suffer from acne.

An average person gets confused between acne and other skin disorders. Generally, words such as comedo, papule, cyst, pustule and nodule are used to refer to acne. These are types of lesions of acne.

Lesion:
Lesion refers to any change occurring in the body tissue caused due to injury or disease. So now you can understand that acne lesions refer to any change made in the skin by a disease in sebaceous follicle.

Comedo :
A sebaceous follicle which gets plugged along with sebum or dead cells from the inner portion of the sebaceous follicle, sometimes bacteria and tiny hair is known as Comedo. This is generally known as 'Blackhead'.

Papule:
A solid lesion which is slightly elevated over and above the skin's surface is known as 'Papule'.

Pustule:
A 'Pustule' is dome-shaped lesion that contains pus which is a mixture of dead skin cells, bacteria and white blood cells.

Nodule:
A nodule is very similar to a papule as it is also dome-shaped or sometimes irregularly-shaped solid lesion. But inflammation occurs in a nodule and it has its roots deep inside the skin which may cause tissue destruction.