| The hallmark of acne vulgaris is the comedo, commonly known as the blackhead. |
| If the plugged follicle, or comedo, stays beneath the skin, it is called a closed comedo and produces a white bump called a whitehead. |
| A comedo occurs when an oil follicle becomes plugged with oil, dead skin, tiny hairs or bacteria. |
| The comedo consists of a mixture of keratinous debris and sebum that lodges in the mouth of the pilosebaceous duct. |
| In our case, the senile degeneration of connective tissue is suspected to be the occasion of comedo formation. |
| If the plug enlarges and is on the surface of the skin, exposed to the air, it is called an open comedo, or blackhead. |
