Chapter 2. Acne Vulgaris


A disease of infundibulosebaceous units, especially infundibula, that may manifest itself solely as noninflammatory lesions, i.e., comedones and intact cysts, or as inflammatory lesions, i.e., papules, nodules, and pustules. The process may resolve without residua or with scars of different types, e.g., keloidal or atrophic, including cribriform. The condition usually affects adolescents, but may at times be seen in neonates and young adults.

Virtually every adolescent is affected by acne vulgaris, if only in a mild form. In adolescents and young adults it may persist for years, whereas in neonates it usually lasts for weeks or a few months. The most severe expressions of acne occur in males.

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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.

Integration: Unifying Concept

Every textbook of dermatology and dermatopathology asserts that acne vulgaris is a disease of the hair follicle. That contention is dead wrong; the follicle (bulb, stem, and isthmus) is unaffected. It is infundibular epidermis. i.e., the infundibulum, that is essential to the process.

The infundibulum-centered acne vulgaris and variants of it seem to be a single pathologic process. The spectrum of its severity ranges from comedones and inflamed papules that resolve without residua to fluctuant and draining sinuses that heal with ugly scars. But whether the condition is called acne vulgaris, acne conglobata, acne keloidalis, hidradenitis suppurativa, or dissecting cellulitis of the scalp (perifolliculitis capitis abscedens et suffodiens), the process is fundamentally the same.

Inflammatory cells, neutrophils chief among them, appear first around and then within infundibula. If the collection of neutrophils is confined to an infundibulum, the lesion is a pustule. If the process is more florid and the collection of neutrophils is so great that much of an infundibulofollicular unit is obscured by it, pseudocarcinomatous proliferation of infundibular keratocytes develops in an attempt to contain it. The result is one or more of a constellation of acne conglobata, acne keloidalis, dissecting cellulitis of the scalp, and hidradenitis suppurativa. The legitimacy of the concept that acne is basically a single pathologic process seems to be verified by the fact that all of its manifestation—among them, vulgaris, conglobata, keloidalis, dissecting cellulitis, and hidradenitis suppurativa—may be present in one person. For acne, in any of its expressions, to come into being requires the play of androgens on the infundibulosebaceous unit.


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Fig. 2-1

The face is the favored site.

Individual Lesions


Fig. 2-2

Comedones may be “open” (black) and “closed” (white).


Fig. 2-3

Comedones, “open” and “closed,” the latter being synonymous with milia.


Fig. 2-4

“Open” comedones are present mostly, but milia are, too.


Fig. 2-5

A cluster of comedones situated on an uncommon site.


Fig. 2-6

Comedones, inflamed papules, and tiny atrophic scars.


Fig. 2-7

Comedones, inflamed papules, and tiny pitted scars.


Fig. 2-8

Comedones, patulous infundibula, and small atrophic scars.


Fig. 2-9

Comedones, patulous infundibula, and tiny atrophic scars.


Fig. 2-10

Inflamed papules and nodules, as well as scars. The nodules represent the effects of rupture of infundibular cysts.


Fig. 2-11 A

The upper part of the chest is a common site, as is the upper part of the back.


Fig. 2-11 B

The upper part of the chest is a common site, as is the upper part of the back.


Fig. 2-12 A

Comedones, patulous infundibula, inflamed papules, pustules, hemorrhagic crusts, and scars; (b) closeup view of (a).


Fig. 2-12 B

Comedones, patulous infundibula, inflamed papules, pustules, hemorrhagic crusts, and scars; (b) closeup view of (a).


Fig. 2-13

Comedones, patulous ostia of infundibula, inflamed papules, inflamed nodules (ruptured infundibular cysts), and scars.


Fig. 2-14

Inflamed papules, some of them excoriated (“acneexcoriée des jeunes filles” because it occurs mostlyin young girls).


Fig. 2-15

Comedones, inflamed papules (some of them excoriated), and scars.


Fig. 2-16

Comedones, inflamed papules, and a few pustules.


Fig. 2-17

Inflamed papules and papulopustules.


Fig. 2-18

Patulous ostia of infundibula, inflamed papules, pustules, and scars.


Fig. 2-19

Inflamed papules and nodules, as well as papulopustules, patulous ostia, and scars.


Fig. 2-20

Patulous ostia of infundibula, inflamed papules, pustules, and scars.


Fig. 2-21

Inflamed papules and papulopustules, and residual hyperpigmented atrophic scars.


Fig. 2-22

Inflamed papules, papulopustules, pustules, and crusts.


Fig. 2-23

Inflamed papules, papulopustules, and pustules.


Fig. 2-24

Inflamed papules, inflamed nodules, and papulopustules.


Fig. 2-25

Inflamed papules, pustules, and crusts.


Fig. 2-26

Inflamed papules, papulopustules, erosions, and hemorrhagic crusts. The erosions are secondary to excoriation.


Fig. 2-27

Excoriated papules.


Fig. 2-28

Inflamed papules and plaques, erosions, hemorrhagic crusts, and scars.


Fig. 2-29

Inflamed plaque, erosions, hemorrhagic crusts, and pustules.


Fig. 2-30

Inflamed papules and plaques, hemorrhagic crusts, and scars.


Fig. 2-31 A

Inflamed papules, erosions, large vegetative hemorrhagic crusts, and scars.


Fig. 2-31 B

Inflamed papules, erosions, large vegetative hemorrhagic crusts, and scars.


Fig. 2-32

Papules, nodules, scars, and crusts.


Fig. 2-33

Pitted scars.


Fig. 2-34

Atrophic scars.


Fig. 2-35

Atrophic and hypertrophic scars.


Fig. 2-36

Many small keloids.


Fig. 2-37

Large keloids on the chest, and inflamed papules and scars on the face.


Fig. 2-38


Neonatal Acne


Fig. 2-39

Papulopustules and pustules.


Fig. 2-40

Inflamed papules (some of them purpuric) and papulopustules.


Fig. 2-41

Inflamed papules and milia.

Acne Keloidalis


Fig. 2-42

Infundibulocentric pustules and keloidal papules.


Fig. 2-43

Comedones, infundibular cysts, pustules, and keloids.


Fig. 2-44

Keloids with tufted hairs.

Hidradenitis Suppurativa


Fig. 2-45

Patulous ostia of infundibula, pus at ostia of sinus tracts, noninflamed and inflamed nodules, an ulcer, and linear scars.


Fig. 2-46

Markedly patulous ostia of infundibula, some representing the opening of sinuses, papules, nodules, and scars.


Fig. 2-47

Patulous ostia of sinuses, some having discharged pus, nodules, and hypertrophic scars.


Fig. 2-48

Scars at sites of sinuses.


Fig. 2-49

Patulous ostia of sinuses and depressed hyperpigmented scars.

Steroid Acne


Fig. 2-50

Monomorphous infundibular papules.


Fig. 2-51

Monomorphous infundibular papules in a patient in intensive care.


Fig. 2-52 A

Monomorphous infundibular papules and papulopustules.


Fig. 2-52 B

Monomorphous infundibular papules and papulopustules.


Fig. 2-52 C

Widespread discrete papules and papulopustules are all infundibulocentric.



Fig. 2-53

Cluster of comedones and infundibular cysts on sun-damaged skin.


Fig. 2-54 A

Numerous comedones and infundibular cysts of different sizes in clusters on skin injured badly by sunlight.


Fig. 2-54 B

Numerous comedones and infundibular cysts of different sizes in clusters on skin injured badly by sunlight.

New! Additional Images


Fig. 2-55

Acne vulgaris: Papules, papulopustules, pustules, nodules, and atrophic scars, as well as patulous ostia of infundibula that previously housed a comedo.


Fig. 2-56

Acne: Comedones, papules, papulopustules, pustules, and hypopigmented atrophic scars.


Fig. 2-57

Acne: Comedones, papules, and atrophic scars.


Fig. 2-58

Acne keloidalis. Papules, some scaly, others crusted of acne keloidalis.


Fig. 2-59

Acne conglobata. Comedones, papules, papulopustules, and honey-colored and hemorrhagic crusts, some of which have peculiar geometric outlines by virtue of lesions having become confluent, of acne conglobata.


Fig. 2-60

Acne. Comedones, papules, papulopustules, and pustules.


Fig. 2-61

Acne. Numerous milia, i.e., tiny infundibular cysts.


Fig. 2-62

Acne. Tiny atrophic scars.


Fig. 2-63

Acne keloidalis. Comedones, milia, keloids, and atrophic scars of acne keloidalis.


Fig. 2-64

Steroid acne. Papules, situated mostly in the center of the face, are a result of topical application for months of high-potency corticosteroids, of steroid acne.


Fig. 2-65

Steroid acne. Papules and papulopustules, each situated at the ostium of an infundibulum, a result of systemic administration of corticosteroid (steroid acne).


Fig. 2-66

A plum-colored nodule, the result of rupture of an infundibular cyst, situated above a linear scar within which are dilated ostia of infundibula, each of which represents an opening of a pilonidal sinus.


Fig. 2-67 A

Acne vulgaris. Papules, papulopustules, and hemorrhagic crusts.


Fig. 2-67 B

Acne vulgaris. Papules, papulopustules, and hemorrhagic crusts.


Fig. 2-68

Favre-Racouchot syndrome. Comedones and milia (small infundibular cysts) of Favre-Racouchot syndrome consequent to injury of skin by rays of the sun received for many decades. There also are seborrheic keratoses.


Fig. 2-69

Neonatal acne. Milia, i.e., tiny infundibular cysts, range from pinpoint to papular and cover most of the face of a neonate (neonatal acne).