Differentiating Epidermal And Dermal Pigmented Lesions

 

Introduction

Pigmented lesions are among the most common aesthetic concerns faced in dermatology and medical aesthetics. Understanding whether pigmentation occurs in the epidermis or dermis is critical for accurate diagnosis and the selection of appropriate treatment methods. At NewAngie, we are committed to providing clear medical insights and advanced laser technologies that support clinicians in delivering safe and effective outcomes.

 

How to Differentiate Epidermal and Dermal Lesions

1. Observe Color and Borders

• Epidermal lesions: lighter in color, mostly brown or yellow-brown, with clear borders, such as freckles, sunspots, and age spots.
• Dermal lesions: darker in color, appearing gray-blue, bluish-gray, or brown-blue, with blurred borders, such as Ota's nevus and nevus of Hori.

2. Check Distribution

• Epidermal lesions: commonly appear on sun-exposed areas of the face. For example, freckles are often found on the bridge of the nose and cheeks, while age spots may appear on the face and back of the hands.
• Dermal lesions: usually occur on the cheekbones and around the eyes. Ota's nevus often follows the distribution of the trigeminal nerve, while nevus of Hori commonly appears on the zygomatic region.

3. Understand the Causes

• Epidermal lesions: often caused by sun exposure, genetics, and skin aging. For instance, sunspots form after sun exposure, while freckles are related to heredity.
• Dermal lesions: associated with genetics, endocrine factors, vascular issues, or chronic inflammation of subcutaneous tissue. Ota's nevus may be related to heredity.

 

Epidermal Lesions

(Freckles)

A pigmented disorder characterized by yellow-brown spots that appear on sun-exposed areas.
Caused by an increase in the number of melanocytes in the epidermis.

Clinical Features:

1. Usually appears between ages 5–10, worsens during puberty, and increases in number with age.
2. Related to seasonal sun exposure: worsens after sun, more severe in summer, lighter in winter.
3. Does not elevate or depress the skin surface, no symptoms, no self-healing.
4. Recommended treatment: 532nm wavelength, energy 150–300mj, spot size 3–4, frequency 1, single pass. Clinical endpoint: frost-like reaction, redness and swelling after 10 minutes.
5. Patients with darker skin should avoid 532nm laser; 755nm can be used instead to prevent hyperpigmentation.

 

(Age Spots / Seborrheic Keratosis)

A benign pigmented disorder occurring mostly in elderly individuals, also called seborrheic keratosis.
Caused by papillomatous proliferation of basal layer cells, with significant melanocyte proliferation.

Clinical Features:

1. Common in people over 50, especially on the head, face, trunk, and upper limbs.
2. Gradually increases with age, color darkens to brown or black, clear borders, surface may be slightly raised.
3. No symptoms, no self-healing, related to sun exposure, metabolism, and immunity.
4. Recommended treatment: 532nm wavelength, energy 150–300mj, spot size 3–4, frequency 1, single pass. Clinical endpoint: frost-like reaction, redness and swelling after 10 minutes.
5. For raised, dark, and larger lesions, fractional CO2 laser is recommended.

 

(Café-au-lait Spots)

A pigmented disorder characterized by regular, café-colored patches.
Caused by an increase in both total melanin and melanocyte numbers in the epidermis.

Clinical Features:

1. May appear in early childhood or be present at birth, enlarging and increasing in number with age; considered a type of birthmark.
2. Can occur anywhere on the body, color is café-brown.
3. Flat with the skin surface, no symptoms, unrelated to seasons or sun exposure.

Recommended treatment:

532nm wavelength, energy 150–300mj, spot size 3–5, frequency 2–3 (burst mode, single pass). Clinical endpoint: frost-like reaction, redness and swelling after 10 minutes. 3–5 sessions may show results but not suitable for darker-skinned patients.

Alternatively, 1064nm wavelength, energy 300–500mj, spot size 6–8, frequency 6–8 (uniform scan mode, no scabbing, no skin damage, mild pain, but requires multiple sessions). Clinical studies suggest 20–40 treatments may be needed; suitable for darker-skinned patients.

 

Dermal Lesions

(Melasma)

A chronic, difficult-to-treat pigmented disorder common in women of childbearing age. Characterized by symmetrical brown spots or patches on the cheeks or forehead, known as the "king of pigmentation."

Melanin is synthesized and secreted by melanocytes in the epidermis. Only when the basement membrane between the dermis and epidermis is damaged can melanin drop into the dermis. Thus, melasma can be classified as epidermal or mixed type depending on the deposition site.

Clinical Features:

1. Related to endocrine factors, hormones, sleep, mood, and genetics. Easily triggered, considered an "active" pigmentation.
2. Recommended treatment: 1064nm wavelength, uniform scan mode, energy 300–500, spot size 6–8, frequency 6–8, 2–3 passes. Clinical endpoint: slight redness.

Treatment can gradually lighten pigmentation but cannot fully remove it. Combination therapy is advised, such as mesotherapy with brightening solutions, improved sleep, barrier repair, oral tranexamic acid, topical hydroquinone cream, and strict sun protection.

⚠️ Note: Laser/light treatments are not recommended during the sensitive period.
(Sensitive period = when the skin barrier is damaged, redness is present, pigmentation is darker, or inflammation exists. In such cases, repair and stabilization should be done before laser treatment.)

 

(Nevus of Hori – Zygomatic Area)

Characterized by symmetrical gray-black, dark brown, or gray-brown spots on the zygomatic region.

Caused during embryonic development when melanocytes from the neural crest fail to migrate through the epidermal-dermal junction and remain in the dermis.

Clinical Features:

1. Occurs mostly in women, with a female-to-male ratio of 13–18:1. Onset typically between ages 16–40, sometimes with family history.
2. Symmetrical distribution on the cheekbones, averaging 10–20 lesions, gray-black or dark brown in color.
3. Lesions are oval, 1–5mm in diameter, with clear borders, flat with the skin surface, no symptoms, unrelated to seasons or sun exposure.
4. Recommended treatment: 1064nm wavelength, spot size 4–6, energy 400–800mj, frequency 1–3, 1–2 passes. Clinical endpoint: erythema or pinpoint bleeding.

 

Conclusion

The differentiation between epidermal and dermal pigmented lesions is essential for guiding safe and effective treatment choices. By combining precise clinical observation with advanced laser technologies, practitioners can better tailor therapies to patient needs.

At NewAngie, we continue to support clinics, hospitals, and aesthetic centers worldwide with professional equipment, innovative laser platforms, and ongoing clinical expertise. For more information on our pigmentation treatment solutions or to request a consultation, please contact our team.