Pigmentary demarcation lines (PDL), also known as Futcher–Voigt lines, are more easily observed in SOC due to the greater contrast with hypopigmented skin. Approximately 6% of patients with PDL present facial involvement (types F, G, and H) (Fig. 1).9

Fig. 1.

Facial pigmentary demarcation lines. (A) Diagram illustrating the location of the lines. (B, C) Asian patient with type G lines (black arrows), forming a “W” shape at the lateral canthus of the right eye. Dermoscopy showed accentuation of the facial pseudoreticular pattern (white arrows) and a granular white pattern (white arrowheads).

A recent article demonstrated that >80% of women with facial PDL present alterations of the sexual hormonal axis.10 Clinically, they appear as well-defined hyperpigmented lines: type F forms a “V” shape on the lateral face between the temple and malar area; type G forms a “W” shape; and type H extends from the angle of the mouth to the chin.11

Dermoscopic findings include exaggeration of the normal facial pseudoreticular pattern12 and white dots arranged in a granular pattern.13

Melasma may reach a prevalence of 10–30% in SOC, or even higher when additional risk factors are present.14 It can be disabling, with depression rates of around 50%.15 It typically develops between 20 and 40 years of age and presents as irregular brown macules with well-defined borders in photoexposed areas, often with areas of “spared” skin. Facial melasma is classified as centrofacial (Fig. 2A–C) or peripheral.14,16 The most common dermoscopic finding is accentuation of the facial pseudoreticular pattern. Brown dots and globules may be observed (although not predominating), along with annular or arcuate structures and telangiectasias.17 A recent study demonstrated that the reticuloglobular pattern was more prominent in epidermal melasma, whereas granular or dotted patterns were observed in dermal melasma.18 Unlike ochronosis, follicular openings are preserved in melasma.12,17

Fig. 2.

(A, B) Melasma in a 42-year-old Latin American man. (A) Irregular brown macules with areas of spared skin, predominantly on the cheeks. (B) Dermoscopy shows a prominent pseudoreticular pattern (black arrows), arcuate structures (black arrowheads), and lighter areas of spared skin (white arrows). Note the preservation of follicular units (white arrowheads). (C) Melasma on the cheek of a Latin American patient. (D) Post-inflammatory hyperpigmentation in a woman of African ancestry, with brown macules on the forehead and eyelids secondary to atopic dermatitis. (E) Post-inflammatory hyperpigmentation in a young man due to beard folliculitis. (F) Frontal post-inflammatory hyperpigmentation secondary to prayer in a Muslim man.

Post-inflammatory hyperpigmentation (PIH) represents pigmentation due to a previous inflammatory process.19 Clinically, it is recognized by the appearance of well-defined brown macules in areas of prior inflammation, with a latency period ranging from several days to several months (Fig. 2D–F).19 PIH may be particularly prolonged in SOC, sometimes persisting for 2–5 years.20 Dermoscopic findings in PIH are not well described in the literature. An accentuated pseudoreticular pattern with light- or dark-brown globules and dots sparing follicular openings may be observed. Pigmentation appears dark brown when the pigment is located in the epidermis or superficial dermis and grayish when deposited more deeply.21

Drug-induced hyperpigmentation is classically associated with tetracyclines, nonsteroidal anti-inflammatory drugs, antimalarials, antipsychotics, amiodarone, diltiazem, or certain antiretroviral drugs.22 Its pathophysiology is complex: some drugs induce melanin accumulation (e.g., hydroxychloroquine), others stimulate melanin synthesis (e.g., lipofuscin), or lead to iron deposition (e.g., minocycline).23 Certain drugs such as voriconazole may induce phototoxic reactions.24 Some drugs have been particularly associated with facial pigmentation, including sunitinib (yellowish hyperpigmentation), phenytoin, polymyxin B, diltiazem, or imipramine.22 Clinically, drug-induced hyperpigmentation appears as hyperpigmented macules with focal or diffuse facial involvement, sometimes accompanied by pigmentation in other body areas.22,23 Only 1 dermoscopic description has been reported in the literature, showing accentuation of the facial pseudoreticular pattern with light- or dark-brown dots and globules.25

The late phase of fixed drug eruption (FDE) may present with isolated pigmentation. Dermoscopy in FDE shows pigment dots and globules with different shades ranging from brown to gray.12

Acanthosis nigricans (AN) presents with grayish-brown hyperpigmented plaques with a velvety texture in flexural areas, particularly the neck, axillae, and groin, and less frequently on the face (Fig. 3). It is more common in adult SOC populations and is frequently associated with obesity and insulin resistance. Some authors reserve the term AN for cases not associated with drugs, neoplasms, or syndromic conditions, referring to obesity-related cases as pseudoacanthosis nigricans.26 Dermoscopically, AN shows a pattern known as “sulci and gyri/cristae,” characterized by accentuated skin grooves and ridges, sometimes hyperkeratotic and more pigmented, on a grayish-brown “dirty” background27 resembling “crocodile skin.”21 Occasionally, dark-brown dots or globules and, more rarely, telangiectasias may also be observed.25

Fig. 3.

(A, B) Acanthosis nigricans in a Central American man. (A) Brownish macules with a velvety appearance predominantly on both cheeks and the supraciliary areas. (B) Dermoscopy shows a “sulci and gyri/cristae” pattern (black arrows) along with follicular plugs (black arrowheads). (C, D) Acanthosis nigricans in an Indian man. (C) Brownish velvety macules on the cheek. Note the acanthosis nigricans on the neck. (D) Dermoscopy shows a “sulci and gyri/cristae” pattern (black arrows).

Frictional melanosis (FM) is also more common in SOC (particularly in individuals from India). It appears in areas subjected to chronic or repeated friction. Clinically, it presents as well-defined dark-brown macules and plaques in areas exposed to trauma (Fig. 4). It is important to ask about possible causes of the lesions (e.g., forehead lesions caused by friction during prayer).28 Mutalik et al. described 6 clinical patterns in facial FM: zygomatic–supraorbital, metomelanosis (forehead), panfacial, parafacial, perioral, and mixed. These patterns show a characteristic symmetrical distribution with uniform brown-black pigmentation without textural changes.29 In contrast to FM, macular amyloidosis usually does not affect the face, tends to be more pruritic, and shows superficial amyloid deposition on histopathology. Dermoscopically, the most frequent finding in FM is exaggeration of the facial pseudoreticular pattern.12,29 Dark-brown or grayish dots and globules and prominent follicular openings have also been described.25,28

Fig. 4.

(A–C) Frictional melanosis secondary to allergic rhinitis in a 32-year-old African woman. (A) Hyperpigmented macules in the nasal region. (B) Repetitive gesture performed by the patient (frequent nasal rubbing). (C) Dermoscopy showing exaggeration of the facial pseudoreticular pattern (black arrows) and diffuse brown-gray dots/globules (black arrowheads).

Seborrheic melanosis (SM), also known as sebomelanosis, is an entity almost exclusively observed in individuals with skin of color (SOC) (Fig. 5). For most authors, it is considered a post-inflammatory sequela of seborrheic dermatitis. However, cases of SM have also been described in patients without a prior history of seborrheic dermatitis and who are asymptomatic. SM is characterized by hyperpigmented macules and thin plaques with very superficial scaling, predominantly affecting the nasal grooves and nasolabial folds. It also typically involves the inferior nasal fold or the perioral region. It may or may not be pruritic and can involve other body areas such as the scalp or trunk.30,31 Dermoscopically, a prominent pseudoreticular pattern, brown granular structures, poorly defined vessels, prominent follicular openings, and yellowish-white perifollicular sebaceous scales are observed.12,30

Fig. 5.

(A, B) Thirty-year-old African woman with hyperpigmented lesions in the nasolabial folds and alar grooves. (A) Dark-brown macules in the alar grooves and nasolabial folds. (B) Dermoscopy: whitish scales (black arrows), predominantly in the alar groove, with background hyperpigmentation. (C, D) Latin American woman with pigmentation in the nasal groove and perioral region due to seborrheic dermatitis. Dermoscopy of the nasal groove showed prominent follicular openings, mild scaling, telangiectasias, and diffuse pigment.

Nevus of Ota, also known as nevus fuscocaeruleus ophthalmomaxillaris, is an oculodermal melanocytosis characterized by coalescent macules distributed along the V1/V2 branches of the trigeminal nerve (Fig. 6A–C). It is more common in women of Asian or African ancestry. In 90% of cases it is unilateral and involves the sclera in 60% of patients.32 There is a slight increased risk of glaucoma, and rare cases of transformation into uveal or cutaneous melanoma have been described.32,33 Therefore, patients with nevus of Ota should undergo ophthalmologic follow-up.34 Dermoscopic features include structureless blue-gray areas and scattered brown-gray dots.12,35

Fig. 6.

(A–C) Nevus of Ota. (A) Blue-gray pigmented macule on the right hemiface, predominantly in the V1 and V2 territories. (B) Dermoscopy shows blue-gray coloration with light-brown and some lighter areas within the nevus. Photographs courtesy of Dr. Verónica Echeverry. (D–F) Lichen planus pigmentosus in a Latin American woman. (D–E) Grayish-brown macules affecting the entire face, predominantly on the cheeks (black arrows). (F) Dermoscopy shows perifollicular brown-gray dots and globules (black arrowheads) without obliteration of follicular openings.

Lichen planus pigmentosus (LPP) is characterized by oval brown to gray-brown macules and plaques, predominantly affecting the preauricular and temporal regions, neck, cheeks, and/or intertriginous areas (Fig. 6D–F). Some authors classify LPP within acquired dermal macular hyperpigmentation (ADMH), which includes several dermal facial hyperpigmentation disorders such as pigmented contact dermatitis (Riehl's melanosis) and erythema dyschromicum perstans.12 LPP may sometimes be associated with other variants of lichen planus, such as lichen planopilaris or frontal fibrosing alopecia.36 Dermoscopically, there is accentuation of the facial pseudoreticular pattern with predominant blue-gray and brown dots and globules arranged in arcuate, perifollicular, and mottled patterns (or without a clear pattern),37 without obliteration of follicular openings.25 Other findings include diffuse erythema, telangiectasias, rhomboidal structures, follicular asymmetry, and reduction of vellus hair.38 Mulinari-Brenner et al. recently described additional dermoscopic features including decreased follicular openings, follicular hyperkeratosis, keratotic plugs, perifollicular erythema, simple loop interfollicular vessels, branching vessels, and white dots. Areas of reduced hair density or alopecia may also be observed.39

Riehl's melanosis (RM) predominantly affects SOC, particularly older women. It is characterized by reticulated to diffuse grayish-brown hyperpigmented macules or plaques on the face, neck, and upper chest (Fig. 7A–C). It may occasionally present with pruritus and superficial scaling. It is considered a type IV hypersensitivity reaction triggered by contact allergens such as fragrances, textiles, and cosmetics, although genetic factors, autoimmune alterations, and sun exposure may also contribute.40 Dermoscopically, a marked pseudoreticular pattern may be observed, with predominance of gray dots and globules, telangiectatic vessels, and an erythematous background.17,21,12 These findings are therefore very similar to those seen in LPP. Clinical history is useful to differentiate RM from LPP (history of allergen exposure in RM). Dermoscopic findings more specific to RM include fine scaling, follicular keratotic plugs, perifollicular hypopigmented halos,41 and obliteration of follicular openings.25

Fig. 7.

(A–C) Latin American woman with Riehl's melanosis. (A, B) Dark brown-gray macules and patches diffusely affecting the face, especially the nose, cheeks, and perioral region. (C) Dermoscopy highlights follicular keratotic plugs (black arrows) and perifollicular pigmented halos (black arrowheads). (D, E) Latin American woman with ashy dermatosis. (D) Blue-gray macules on the left cheek. (E) Dermoscopy shows a brown reticular pattern without evident vascular structures.

Exogenous ochronosis (EO) is characterized by dark-brown or even blackish macules and plaques.42 Papules resembling “caviar” (colloid milium) or interspersed atrophic hyperpigmented patches may be observed. Dermoscopically, EO presents with exaggerated facial pseudoreticular pattern, hypopigmented areas, telangiectasias, and dark-brown curvilinear or amorphous structures with obliteration of follicular openings.17,21,12 Histological examination is particularly useful, showing the characteristic ochre-colored “banana bodies” in the upper dermis.12

Maturational hyperpigmentation (MH) is a recently described entity, almost exclusive to SOC (especially individuals from India), characterized by dark-brown macules predominantly on the cheeks, temples, and forehead. Macroscopically, the lesions often show a “granular” surface and poorly defined borders. It is considered a marker of metabolic syndrome.43 Dermoscopically, it shows a nonspecific pattern with a light-brown background overlaid by multiple dark-brown globules and clods. The most distinctive feature is circular to oval dark-brown structures with perifollicular accentuation. Unlike acanthosis nigricans, it does not show sulci or ridges.43,44

Ashy dermatosis (erythema dyschromicum perstans) is a condition of unknown etiology, more common in SOC (Latino, Afro-descendant, and Asian populations). It is characterized by grayish or bluish hyperpigmented macules that appear on the trunk, extremities, neck, and less frequently on the face (Fig. 7D–E). Dermoscopy helps differentiate it from other conditions such as melasma, PIH, fixed drug eruption, and LPP. Dermoscopy typically shows a reticulated pattern with gray and brown networks, grayish or black pigment globules in more advanced lesions, and absence of vascular structures.21,45