Enlarged facial pores are superficial skin structures that are visualized as small openings on the skin corresponding to the openings of the pilosebaceous apparatus. These openings may be impacted with horny follicular plugs consisting of sebaceous debris that appear as open comedones.1 Skin pores is a lay term that is poorly defined in the medical literature and often is categorized in terms of arbitrary circular diameters determined through cosmetic skin analyzers.2 The term refers to pilosebaceous follicular enlargements (with or without open comedonal horny impactions) that can be visualized by the naked eye, most commonly occurring on the face and scalp. These enlarged pores remain a pervasive cosmetic concern that impacts patient quality of life. Enlarged pores are difficult to treat, in part due to lack of knowledge of the pathophysiology; thus, we review the currently proposed causes of enlarged pilosebaceous openings and the treatments in the scope of this pathogenesis with a focus on therapeutic efficacy.
Pathogenesis of Enlarged Facial Pores
It is now thought that seborrhea, loss of skin elasticity and tension, and hair follicle size are most clinically relevant to the pathogenesis of enlarged pores.2 Other potential associated and causative factors include genetic predisposition, acne, comedogenic xenobiotics, chronic photodamage, chronic radiodermatitis, and vitamin A deficiency.1,3
The direct relationship between sebum output and pore size has been well established, particularly in men who generally have higher sebum output levels than women, which likely is testosterone driven.4,5 However, there are contradictory data on whether sex affects pore size, as females also exhibit contributory hormonal factors. Sebum output and pore size increase substantially during the ovulation phase of the female menstrual cycle, likely secondary to increased progesterone affecting sebaceous gland activity.2,4 The presence of acne also is associated with enlarged facial pores, though the extent of seborrhea as a confounding factor is unclear. Furthermore, acne severity does not correlate with increased pore size.5 However, the processes of acne and facial pores are interlinked, given the frequent occurrence of open comedones within the pores.
Skin elasticity and tensile strength when defined visually and mechanically has shown a negative correlation with facial pore size and density.5 It is well known that cutaneous aging and chronic photodamage cause perturbation in the collagen and elastin framework that allows for the skin to maintain its resilient properties.6 Aged and photodamaged skin also demonstrates decreased expression of microfibril-associated glycoprotein-1 (MAGP-1), a crucial component in elastic fiber assembly and skin elasticity in the dermis and perifollicular/pore areas.7
Pore density and size appears to range diversely across ethnicities, though Chinese women exhibit notably lower pore size and density across all ages as compared to other ethnicities.8 Black individuals have aberrant epidermal architecture, defined as the presence of stalagmitelike structures at the dermoepidermal junction, correlating with enlarged pore size compared to other ethnicities.2,8
Treating Enlarged Facial Pores
Treatments for enlarged facial pores primarily aim to decrease sebum production, rejuvenate skin, remove hair, and/or decrease follicular size. Evidence-based studies are limited, and many currently used therapies have not been studied with enlarged facial pores as a primary investigative outcome. Here, we include studies that report efficacy in decreasing pore size specifically. It is important to note the lack of a uniform and objective modality with which to report skin pore size. Studies use a wide range of techniques including patient self-reporting, physician observation, and software image analyzers.
Topical retinoids are vitamin A derivatives, and they are first-line therapies in reversing the aberrant collagen and elastin-associated epidermal and dermal changes that occur with chronological aging and photoaging. Tretinoin, isotretinoin, and tazarotene have shown efficacy in multiple parameters of skin rejuvenation, including facial pores, skin wrinkling, hyperpigmentation, skin laxity, and sebum production.9 However, it is important to note that retinoids treat keratinocyte atypia in acne, and efficacy in facial pores is confounded by improvement in follicular keratinization. Because studies have not distinctly uncoupled this association, it is erroneous to conclude that retinoids reduce facial pore size and density irrespective of concomitant acne vulgaris.
Tazarotene has been evaluated for use in reducing facial pore size. In one investigation, 568 patients with moderate wrinkling or hyperpigmentation were randomized to receive tazarotene cream 0.1% or placebo once daily for 24 weeks and were evaluated for enlarged facial pores as a secondary outcome using a double-blinded physician 5-point scale.10 At week 24, 42% of tazarotene-treated patients achieved improvement of at least 1 point compared to 20% of placebo-treated patients (P<.001). Adverse events were dermatitic, as can be expected of retinoids, leading to a 4% discontinuation rate in the tazarotene group compared to 1% in the placebo group.10