New Ideas For Acne Classification In 2026!

In clinical practice, acne is graded and classified in various ways. Traditional acne grading systems mainly include lesion counting and comprehensive grading methods. Generally speaking, these grading methods are highly subjective and rely heavily on visual observation.

However, a recent study has, for the first time, clearly defined the quantitative relationship between background color, vascular morphology, and the severity of acne inflammation. Let’s learn about it together!

The Pillsbury Clinical Grading System for Acne Vulgaris Severity:

• (A–C) Grade I: Predominantly comedones with scattered inflammatory papules.
• (D–F) Grade II: Comedones present with a moderate number of inflammatory papules and pustules.
• (G–I) Grade III: Numerous inflammatory papules and pustules, with fewer than 3 nodules.

Experimental methods and preparation

1. Study Design: Cross-sectional observational study
2. Study Subjects: 40 patients aged 16-30 years with mild to moderate acne (Pillsbury stage I-II), excluding those who had received anti-acne treatment within the past 2 months.
3. Image Acquisition: Images were taken by the same experienced physician under standardized conditions (polarized light mode, 40x magnification, room temperature 24-26℃). Two representative lesions were selected from each patient, resulting in a total of 80 images.
4. Assessment Indicators: Background color, vascular morphology, vascular distribution, and a pale yellow halo around the hair follicle.
5. Statistical Methods: Chi-square test was used to compare differences between groups, and Cohen’s κ coefficient was used to assess inter-observer agreement.

Acne Analysis Tools

We need detailed data on the patient’s facial acne, considering both macroscopic and microscopic perspectives, and obtaining information on the superficial and deep layers of the acne.

Therefore, we need to utilize two tools: a skin analyzer and a dermoscope.

Skin analyzers, a type of beauty equipment, are available in most beauty salons. They use three-phase imaging to present detailed skin texture in three dimensions, and through AI data analysis, ultimately confirm the current skin issues by comparing 12 indicators.

Dermoscopy, also known as a transillumination microscope, uses oil immersion, light exposure, and optical magnification to observe skin structures that are difficult to see with the naked eye, including the subepidermis, the epidermal-dermal junction, and the papillary dermis. It is characterized by its ease of operation, non-invasiveness, and safety, resulting in high patient acceptance. In recent years, it has become an emerging technology in dermatology, playing an increasingly important role in the diagnosis of skin diseases, and is therefore often referred to as “the dermatologist’s third eye.”

Acne Research Found

1. Key Inflammatory Markers

The study found that a gradual deepening of skin background color from light red to red to dark red was significantly positively correlated with the severity of acne inflammation, and was the only indicator showing statistical difference between the mild and moderate acne groups.

• Mild acne group: 41.7% showed a light red background, and only 8.3% showed a dark red background.
• Moderate acne group: Red and dark red backgrounds each accounted for 38.6%, while light red backgrounds accounted for only 22.7%.

The differences are even more pronounced when analyzed by skin lesion type:

• Comedones: 55.6% with a light red background, only 7.4% with a dark red background.
• Papules: 50.0% with a red background, 25.0% with a dark red background.
• Pustules: 52.9% with a dark red background, only 5.9% with a light red background.

The image above shows the correspondence between background color and inflammation severity in acne dermatology.

A: Light red background (mild inflammation);

B: Red background (moderate inflammation);

C: Dark red background (moderate to severe inflammation).

Easy and most practical conclusions:

1. Grading Calibration: When there is doubt regarding the visual grading, the dermoscopic background color should be used as the standard. A light red background corresponds to mild inflammation, a red background to moderate inflammation, and a dark red background indicates that the inflammation is approaching severe, requiring timely adjustment of the treatment plan.

2. Subclinical Inflammation Identification: For patients with only visible comedones, if a red background appears under dermoscopy, it indicates the presence of subclinical inflammation. Using retinoids alone in this case results in a high recurrence rate, and topical anti-inflammatory treatment should be added earlier.

3. Efficacy Monitoring: The change in background color from dark red to light red after treatment is an early sign of inflammation resolution, occurring 3-5 days earlier than visual lesion regression, thus preventing recurrence caused by premature discontinuation of medication.

Dermoscopy background color and corresponding treatment methods

2. Inflammation Development

The evolution of vascular morphology can promptly reflect the progression of inflammation. The transformation of vascular morphology from punctate to branching to atypical corresponds to the dynamic process of inflammation progressing from localized to diffuse, and from early to late stages; significant differences exist between different lesion types.

Although the overall difference in vascular morphology between the mild to moderate acne groups did not reach statistical significance, the trend was very clear:

• Mild acne: Punctate vessels accounted for 36.1%, and branching vessels accounted for 38.9%.
• Moderate acne: Branching vessels accounted for 52.3%, and atypical vessels accounted for 31.8%.

Analysis by lesion type:

• Acne: 48.1% were punctate vessels, only 14.8% were atypical vessels.
• Papules: 47.2% were branching vessels, 38.9% were atypical vessels.
• Pustules: 58.8% were branching vessels, punctate vessels accounted for only 11.8%.

The image shows the dermoscopic evolution of blood vessel morphology in acne.

D: Punctate vessels (early inflammation);
E: Branching vessels (intermediate inflammation);
F: Atypical vessels (late inflammation, indicated by arrows).

Vascular morphology is a key indicator for predicting changes in acne:

1. Lesion prognosis prediction: Comedones with predominantly punctate vessels have approximately a 20% risk of developing into inflammatory papules; while comedones with branching vessels have a risk exceeding 60%, requiring enhanced intervention.

2. Scar risk assessment: The presence of atypical vessels indicates significant superficial dermal angiogenesis. These lesions have a 2-3 times higher risk of post-inflammatory hyperpigmentation (PIH) and atrophic scars after healing compared to ordinary lesions, necessitating preventative measures.

3. Treatment optimization: For inflammatory papules with predominantly branching vessels, antibiotic treatment alone is ineffective. Combining photodynamic therapy (RTP) with red/blue light or intense pulsed light (IPL) can be used to close the blood vessels and accelerate inflammation resolution.

3. Feature Combination Judgment

Research has found that different types of acne lesions have a characteristic combination pattern of “background color + blood vessel morphology”, which can be used to quickly identify the nature of the lesions and the degree of inflammation with an accuracy rate of over 85%.

• Typical comedones: Light red background + punctate blood vessels + pale yellow halo around hair follicles
• Typical papules: Red background + branching/atypical blood vessels
• Typical pustules: Dark red background + branching blood vessels + central yellowish-white pustule

The image above shows the dermoscopic distribution of blood vessels in acne.

G: Diffuse distribution;

H: Localized distribution;

I: Peripheral distribution.

Acne Treatment Methods

1. Drug treatment methods

Topical medications for acne treatment include retinoids, benzoyl peroxide, antibiotics, and azelaic acid in various concentrations and formulations.

Topical retinoids improve keratinization of the pilosebaceous duct, dissolve microcomedones and comedones, reduce inflammation, and prevent and improve post-inflammatory hyperpigmentation and acne scarring. They also increase skin permeability and can enhance the efficacy of topical antibacterial and anti-inflammatory drugs in combination therapy.

Oral retinoids significantly inhibit sebaceous gland lipid secretion, regulate abnormal keratinization of the pilosebaceous duct, improve the anaerobic environment of the hair follicle thereby reducing the proliferation of Propionibacterium acnes, and have anti-inflammatory and scar-preventing effects. They are currently the only oral medications targeting the four key pathophysiological aspects of acne pathogenesis.

2. Laser therapy

In the current beauty market, there are many photoelectric treatments for acne, such as LED photodynamic blue light, intense pulsed light (IPL) treatment at 530nm/560nm, and 1927nm thulium laser treatment.

LED photo therapy machines use blue light to target cells, activating natural endogenous photosensitizers within pathogens (such as porphyrins and flavins) to produce an endogenous photodynamic effect, thereby killing Propionibacterium acnes. Blue light can also inhibit inflammatory factors related to the pathogenesis of acne, thus improving acne lesions.

IPL (Intense Pulsed Light) has a dual effect on reducing acne due to its selective photothermal effect and the transmission of its high-intensity multicolor light. It can target sebaceous glands, trigger porphyrins, and generate singlet oxygen through photochemical reactions, thereby inhibiting the proliferation of Propionibacterium acnes and suppressing inflammation.

The 1927nm thulium laser is currently a popular device for treating acne. It also utilizes the photothermal effect to transfer heat, and its wavelength can reach the mesoderm (between the epidermis and dermis), effectively killing acne-causing bacteria and treating vasodilation.

Currently, among Liton Laser’s main functional devices, the thulium laser + erbium laser is a representative and popular machine that is both effective and non-invasive. Thulium-erbium lasers have amazing benefits for acne, melasma, and skin tightening!

Frequently Asked Questions

Q1: Why does my acne keep recurring? How should it be diagnosed and treated?

First, avoid risk factors for acne, such as eating less, drinking less milk, and avoiding staying up late. Additionally, if you have severe acne, continue using medication regularly. If your acne has significantly improved, keep your skin in a neutral state, avoiding excessive oiliness. At the same time, focus on repairing your damaged skin barrier; you can use functional skincare products. Once the barrier is repaired, acne is less likely to recur.

Q2: How long should brushing acid remain on the skin? What stage of acne is it suitable for?

The application time depends on the patient’s condition, generally 3-5 minutes, but no more than 5 minutes.

Glycolic acid is mainly used for acne and post-inflammatory hyperpigmentation; salicylic acid is suitable for grade II acne; compound acids (a mixture of glycolic acid and salicylic acid) can be used for all types of acne.

Q3: How does acne form?

Acne pathogenesis is related to four main mechanisms:

1. Excessive sebum secretion: Androgen stimulation or sebaceous gland sensitivity leads to excessive sebum production.
2. Abnormal follicular keratinization: Excessive accumulation of keratinocytes at the hair follicle opening, clogging pores (forming microcomedones).
3. Propionibacterium acnes proliferation: Overgrowth of bacteria within the clogged hair follicles triggers inflammation.
4. Inflammatory response: Bacterial metabolites and immune responses lead to redness, pustules, and even nodules and cysts.

Q4: Does acne need treatment?

Mild acne, without noticeable discomfort, may not require treatment or only simple treatment. However, moderate to severe acne must be treated early, especially in cases with numerous inflammatory lesions and cysts. Untreated acne can easily leave acne scars and pits.

Mild acne: Can be controlled with skincare and topical medications.

Moderate to severe acne: Requires a multi-dimensional combination of medication, physical therapy, proper skincare, skin barrier repair, and even medical aesthetic interventions (IPL, thulium laser, PDT blue light).

Q5: What are the precautions for daily care?

1. Cleansing: Gently cleanse (twice daily), avoiding over-cleansing or rubbing.
2. Moisturizing: Choose oil-free skincare products to maintain the skin barrier.
3. Sun Protection: UV rays can worsen inflammation and pigmentation; physical sunscreens or lightweight sunscreens are recommended.
4. Avoid Squeezing Pimples: This can easily lead to infection and scarring.
5. Dietary Adjustments: Reduce intake of high-sugar and high-dairy products, and eat more vegetables and Omega-3 fatty acids (such as those from deep-sea fish).

Q6: What are the causes of acne?

• High oil content in food and dry climate.
• Hormonal imbalances.
• Inadequate skin cleansing.
• Digestive system problems.
• Changes in hair follicles.
• Excessive stress.
• Irregular lifestyle.

Conclusion

1. For acne-like lesions that are difficult to distinguish (such as rosacea papules and folliculitis), dermoscopic features are of significant diagnostic value. Rosacea typically presents as diffuse erythema with polymorphic blood vessels, while acne presents as localized background color changes with central follicular vessels.

2. Comedonal lesions are predominantly characterized by punctate vessels, papular lesions by branching and atypical vessels, and pustular lesions by branching vessels. The vascular morphology changes from simple to complex as inflammation worsens.