A study on dermoscopy of facial melanosis

INTRODUCTION

Patients with facial melanosis comprise a major group in all dermatology clinics. The vast majority of them are linked to alterations in the melanin pigment.¹ Consultations in the last few years have increased due to esthetic facial concerns such as melasma, lichen planus pigmentosus (LPP), and periorbital hyperpigmentation (POH).^2-5 Dermoscopy has helped to define and ascertain certain differentials not normally visible to the unaided eye.

MATERIAL AND METHODS

Various patients of different disorders mentioned above visiting the Dermatology Outpatient Department from December 2019 to October 2020 were examined dermoscopically. The dermoscopic features were analyzed using a hand-held Dermlite DL4N dermoscope.

RESULTS

Fifty patients (15 males and 35 females) with acquired facial melanosis were included in the study after obtaining an informed written consent.

There were 5 patients of Nevus of Ota [Figure 1]. Clods and perifollicular sparing (PFS) were seen in all patients of dermoscopy, brown grayish areas with bluish tinge were seen in 4 patients, perifollicular pigmentation (PFP) in some areas was seen in 2 patients along with PFS in other areas and light brown dots were seen in only 1 patient.

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Figure 1:

Clinical and dermoscopic picture of Nevus of Ota.

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There were 10 cases of LPP [Figure 2] included in this study. Various dermoscopic patterns observed were brown/ black dots, globules, and PFS in all 10 patients, and hem-like patterns of pigmentation and reticular pattern of pigmentation (RPP) were observed in nearly 80% of patients. A brown background of pigmentation was seen in 8 patients. A reticular pattern with thick lines was seen in 2 patients with long-standing pigmentation.

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Figure 2:

Clinical and dermoscopic picture of Lichen planus pigmentosus.

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There were 5 patients with topical steroid-dependent facies [Figure 3]. Various dermoscopic patterns were PFS in 100% of patients, dilated and tortuous blood vessels in 4 patients, small linear blood vessels were seen in 2 patients, and blotches of pigmentation with accentuation of pseudonetwork of pigmentation were seen in 60% of patients.

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Figure 3:

Clinical and dermoscopic picture of steroid-dependent facies.

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There were 5 patients of facial acanthosis nigricans [Figure 4] included in the study. Crista cutis, sulcus cutis, and light brown dots were seen in all patients. PFP was seen in 4 patients.

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Figure 4:

Clinical and dermoscopic picture of Acanthosis nigricans.

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Five patients were of pigmentary demarcation lines (PDLs) [Figure 5]. Dermoscopic findings seen were clear borders of abrupt transition, accentuation of pseudoreticular pattern of pigmentation, and dots and clods in all patients. White clods were seen in 3 patients.

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Figure 5:

Clinical and dermoscopic picture of pigment demarcation lines.

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There were 10 patients with POH [Figure 6]. Blotches of pigmentation with PFS were seen in all patients with concomitant PFP in 3 patients. RPP was seen in 8 patients and dots in 3 patients.

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Figure 6:

Clinical and dermoscopic picture of periorbital pigmentation.

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There were 2 patients with pigmentation due to vitamin B12 deficiency [Figure 7] included in our study. Dermoscopic findings noticed in both patients were PFS with mild scaling, perieccrine pigmentation, and brown blotches with a relatively light brown background. There were 4 patients with Ashy dermatosis [Figure 8] whose dermoscopic patterns are noted in this study. All the patients showed (100%) scattered fine dots and dots arranging themselves into arcuate and annular patterns, and background erythema was noted in 3 patients with fine linear vessels. Few globules were seen in between in almost all patients.

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Figure 7:

Clinical and dermoscopic picture of ashy dermatosis.

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Figure 8:

Clinical and dermoscopic picture of pigment contact dermatitis.

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Four patients of pigment contact dermatitis (PCD) [Figure 9] were involved in our study, which showed dots and globules in all patients (100%), background erythema in all patients, blotches in 50% of patients, concentric layered pigment globules in 3 of patients with dots/globules in center of pigmented globules in 50% of patients.

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Figure 9:

Histopathology of acanthosis nigricans. [H&E stain, 10× view]. H&E: Hematoxylin and eosin stain.

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DISCUSSION

These days acquired dermal macular hyperpigmentation (ADMH) is an umbrella term that covers LPP, ashy dermatosis, PCD, and Riehl’s melanosis. Nevus of Ota primarily affects the sclera and ipsilateral facial skin in the distribution of the trigeminal nerve.⁶

The nevus is blue-gray in color due to entrapped melanocytes in the dermis.⁷ In our study, dermoscopic findings in Nevus of Ota [Graph 1] were clods, PFS, brown grayish areas with bluish tinge and dots [Figure 1]. A dermoscopic study done by Elmas and Kilitçi showed dots and brown-gray structureless areas, perifollicular hypopigmentation, white clods, and fine scales in nearly all the patients.⁸ In our study, fine scales and white clods were not seen and dots were seen in only 25% of patients. No white rosettes were seen in our study, as seen by El Kadiri et al.⁹

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Graph 1:

Nevus of Ota. PFP: Perifollicular pigmentation, PFS: Perifollicular sparing.

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LPP is a photodistributed disorder of pigmentation characterized by asymptomatic blue-gray or brown-black macules.^10,11 Dermoscopic patterns of LPP [Graph 2] observed in our study were brown black dots, globules, and PFP in all patients with simultaneous PFS in some, hem-like pattern in nearly 80% of patients, a reticular pattern of pigmentation in 80% of patients with brown black background [Figure 2]. Similar findings were reported in a study done by Ankad et al., Neema et al., and Gupta and Sharma.^12-14

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Graph 2:

Lichen planus pigmentosus. RPP: Reticular pattern of pigmentation, PFP: Perifollicular pigmentation.

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Topical steroid-dependent facies refer to defacement of the face caused by overzealous use of unsupervised topical corticosteroids for prolonged periods which results in various manifestations, e.g., erythema, telangiectasias, and steroid rosacea.^15,16 Dermoscopic features reported in various studies are irregularly dilated tortuous vessels branching vessels giving polygonal appearance along with small nonlinear vessels, red dots, telangiectasias and white-to-strawberry-colored patches along with hypertrichosis.^17,18 In our study [Graph 3], PFS was seen in almost all cases, dilated vessels and tortuous vessels were seen in 80% of cases and small linear vessels in 40% of cases [Figure 3]. Blotches of pigmentation and accentuation of pseudoreticular pigmentation were seen in nearly 60% of patients with melasma using unsupervised topical corticosteroids.

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Graph 3:

Steroid dependent facies. PFS: Perifollicular sparing.

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PDL is areas of abrupt transition between deeply pigmented skin of outer surfaces and lighter inner surfaces.^19,20 Various dermoscopic findings described in studies are clear borders of abrupt transition between more and less pigmented areas along with darker, thicker brown curved lines in more pigmented areas, and blotchy and granular patterns of pigmentation.^21,22 In our study [Graph 4], clear borders of abrupt transition, accentuation of pseudonetwork pattern of pigmentation, and dots/clods [Figure 4] were seen in almost all cases. A new finding noted was the presence of white clods in nearly half of patients.

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Graph 4:

Acanthosis nigricans. PFS: Perifollicular sparing.

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Acanthosis nigricans is asymptomatic velvety hyperpigmentation of skin most commonly involving intertriginous areas. Rarely can it involve face.²³ It is related to obesity, and insulin resistance.^24,25 Dermoscopy of facial acanthosis nigricans shows similar findings to that of flexural acanthosis nigricans namely crista cutis, sulcus cutis, and hyperpigmented dots.²⁶ There have been very few studies on dermoscopic patterns seen in facial Acanthosis nigricans. In our study [Graph 5], Crista cutis, sulcus cutis, and light brown dots [Figure 5] were seen in all cases and PFS is seen in 75% of patients. Histopathology of acanthosis nigricans [Figure 9] showed hyperkeratosis, acanthosis, papillomatosis, follicular plugging, and hypermelanization of the basal layer. Early diagnosis and further confirmation by dermoscopy can help to differentiate it from other causes of facial melanosis, particularly maturational hyperpigmentation which appears clinically similar and thus can eliminate the need for biopsy.

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Graph 5:

Pigmentary demarcation lines. PFS: Perifollicular sparing, psRP: Pseudo reticular pattern.

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POH is a blurred entity encountered commonly in dermatology outpatient departments characterized by brown or dark brown macular pigmentation around the eyes.²⁷ It is more common in females and the 16–25 age group according to a study done in India.²⁸ POH may be genetic or acquired secondary to nutritional deficiencies, sleep disturbances, contact dermatitis, or allergic dermatitis.²⁹ Dermoscopic findings described in acquired dermal macular pigmentation in an Indian study are dots and globules in early cases, while in late ADMH diffuse pattern of pigmentation sparing only eccrine openings is seen.³⁰ In our study, blotches of pigmentation and PFS were seen in all cases with reticular pigmentation in nearly 83% of patients. PFP was seen in nearly 33% of long-standing cases of POH. Dots were seen in 33% of patients [Figure 6 and Graph 6].

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Graph 6:

Periorbital hyperpigmentation. PFS: Perifollicular sparing, RPP: Reticular pattern of pigmentation, PFP: Perifollicular pigmentation.

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Vitamin B12 serves as an essential co-enzyme involved in deoxyribonucleic acid synthesis.^31,32 Common cutaneous presentations of vitamin B12 deficiency include hyperpigmentation, hair and nail changes, and glossitis. Accurate identification of cutaneous findings and systemic involvement is imperative in establishing diagnosis. This paper addresses dermoscopic findings of vitamin B12 deficiency, so far lacking in literature. Dermoscopic findings in our study of hyperpigmentation due to vitamin B12 deficiency were brownish-black pigmented clods and blotches. Additional studies are required to confirm the findings.

Ashy dermatosis is grayish macular pigmentation of unknown etiology.³³ It has been associated with drugs like omeprazole, fluoxetine, infections like hepatitis C, human immunodeficiency virus, enteroviruses, cobalt allergy, and Chinese herbal extracts.^34-37 Dermoscopic findings in various studies showed gray bluish small dots and globule-forming circles, irregular and angulated lines arranged in a reticular pattern over a blue, brown, or pinkish background without any accentuation of the pseudoreticular pigment network.^14,38 Findings in our study [Graph 7] were very similar to the study done by Elmas et al.³⁹ which included abundant dots, scattered as well as arranging themselves into arcuate and annular patterns [Figure 7]. Background erythema and fine linear vessels were also seen in 3 patients. Dots are present in both LPP and ashy dermatosis but in ashy dermatosis, dots were more abundant and brown as compared to LPP in which brown to black dots were present. Furthermore, in Ashy dermatosis, the pseudoreticular or reticular pigmentary network is not seen.

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Graph 7:

Ashy dermatosis.

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Reihl’s melanosis is a variant of PCD most commonly attributed to fragrances and chemicals in cosmetics. In our study, we included four patients having PCD due to hair dyes with prominent pigmentation over the forehead, temporal, and zygomatic regions. Dermoscopic patterns described in various studies are pseudo-networks with gray dots, pigment globules focal telangiectasia, and scales in patients.^12,40 In our study, dermoscopic findings [Graph 8] were seen as dots, globules [Figure 8], and PFP (more often than sparing). Interestingly, a new finding observed in our study is concentric layered pigment globules forming arcuate or annular patterns and dots/globules surrounded by light brown which is further surrounded by dark brown pigmentation. The histopathology of PCD [Figure 10] showed epidermal atrophy and liquefactive degeneration of the basal layer with pigment incontinence.

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Graph 8:

Pigment contact dermatitis.

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Figure 10:

Histopathology of pigment contact dermatitis. [H&E stain, 40x magnification]. H&E: Hematoxylin and eosin stain. CD: Contact dermatitis

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CONCLUSION

Dermoscopy is an important tool to distinguish various hypermelanotic disorders, especially when the patient refuses skin biopsy.