Acne Scars



Acne Scars





8.4.i
Atrophic Acne Scars

Karina C. Furlan

Brian W. Petersen

Murad Alam


BACKGROUND

Acne is an exceedingly common condition, with the vast majority adolescents impacted to some degree at some point in their lives.1 Although the time of onset is typically in the teen years, coincident with puberty, patients may have acne for the first time later in adulthood, with this particularly notable in women.2,3 Inflammatory lesions of acne can be painful. Moreover, the psychosocial impact of acne on individual patients can be immense, with the associated perceived disfigurement of active acne resulting in self-consciousness and depression in adolescents and the associated scarring further exacerbating these effects. Atrophic scars, the most common type of acne scars,4,5 can have a profound impact on self-image, lead to self-imposed social isolation, and otherwise impair the process of normal socialization during late childhood and early adulthood. Affected patients are literally “scarred for life.”


PRESENTATION

Patients may present as early as adolescence or in adulthood with a complaint of scars associated with a history of acne. Scars may present with various lesion morphologies, and the distribution is usually on the face but may involve the torso or extremities.



PATHOGENESIS

The pathogenesis of acne is multifactorial, and important contributors are elevated sebum levels, anomalies in the composition of sebum, heightened androgenic hormonal influences, follicular colonization by Propionibacterium acnes, and impaired follicular differentiation resulting in hyperkeratinization.11 The induction of 5-lipoxygenase and cyclooxygenase-2 in sebaceous glands causes production of proinflammatory lipids.12,13 Keratinocytes and sebocytes are stimulated to become more active by the presence of P acnes.14 Monocytes and macrophages in the pilosebaceous units cause the production and release
of various cytokines and chemokines, including interleukin (IL)-8 and IL-12.15

There is a 3-stage process by which an acne lesion results in a scar. Specifically, inflammation is followed by granulation tissue formation and matrix remodeling. In inflammation, an initial vasoconstrictive stimulus is followed by vasodilatation, which manifests as erythema. This erythema, in turn, can result in the erythema and hyperpigmentation routinely seen after resolution of active acne.16 Based on the assessment of histological specimens, Holland et al. determined that the inflammatory process at the sebaceous glands was stronger and slower in patients with acne who tended to develop scars, as compared with those whose acne resolved without scarring. The presumptive conclusion was that early treatment and hence abbreviation of the inflammatory phase in acne may reduce the risk of scarring.17 The formation of granulation tissue, which includes new capillaries as well as new collagen deposition by fibroblasts, is initiated several days after the inflammatory reaction associated with an acne lesion. The early preponderance of type III collagen changes in the mature scar to approximately 80% type I collagen.18 Thereafter, the activity of fibroblasts and keratinocytes activate enzymes that modify the extracellular matrix metalloproteinases (MMPs) and result in tissue remodeling.19 The specific type of MMP activity determines whether atrophic or hypertrophic scars are formed. Lesser activity results in diminished collagen formation and an atrophic scar, and an excessively intense response gives rise to an exophytic growth of fibrotic tissue, or a hypertrophic scar.20

Jun 29, 2020 | Posted by in Dermatology | Comments Off on Acne Scars
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