Beginning with the flow of androgens at puberty, typical lesions of mild to moderately severe acne vulgaris in adolescents come and go for several years, usually disappearing completely and without residua, except at times for patulous infundibula on the nose and malar region. Episodically, the process is more fulminant and prolonged, conglobate lesions being long lasting and healing with unsightly atrophic scars. New lesions of acne keloidalis on a nape may continue to appear as the inflammatory process smoulders well into adulthood. Severe acne that occurs especially on the back in males often resolves with a type of anetoderma that presents itself as atrophic papules, and that is incorrectly designated “macular atrophy.”
A comedo may become progressively larger and eventually be gigantic. In time, the ever-expanding plug of cornified cells causes the wall of an infundibulum to become so thin that eventually it is breached, spewing into the dermis cornified cells, sebaceous secretion, and microorganisms. This event sets in motion an inflammatory reaction marked initially by suppuration, then by granulomatous inflammation, and, in time, by fibrosis. A pustule situated within an infundibulum, in a fashion comparable to a comedo, may become so large that its contents are disgorged into the dermis where they inevitably induce granulomatous inflammation and, sometimes, fibrosis.
If the focus of suppuration in the reticular dermis (and, at times, the subcutaneous fat) becomes very large, a huge abscess forms and the destructive effects of products of the neutrophils that compose it lead invariably to extensive fibrosis. When the epithelium of infundibula and eccrine ducts then proliferates in pseudocarcinomatous fashion in an attempt to “wall off” the abscess, sinus tracts may come into being. If several contiguous abscesses have formed, each being positioned at the site of an infundibulum, the result may be sinus tracts that are interconnected. That phenomenon resolves with extensive fibroplasia.
Acne vulgaris may consist only of comedones, but in most patients, comedones are joined by reddish papules and pustules. That very common expression of acne vulgaris does not, as a rule, resolve with scars. If, however, abscesses form and especially if the process eventuates in draining sinuses, severe scarring is a certainty. Whereas pustules of acne vulgaris may begin to wane in days, abscesses that are followed by granulomatous inflammation and fibrosis may not resolve completely for many months.