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Indian J Dermatol
Indian J Dermatol
IJD
Indian J Dermatol
Indian Journal of Dermatology
0019-5154
1998-3611
Wolters Kluwer - Medknow India

IJD-69-359
10.4103/ijd.ijd_313_23
Correspondences
Dermoscopy of Familial Gigantic Melanocytosis: A Report of Rare Entity
Ankad Balachandra S.
Nikam Balkrishna P. 1
Chigurupati Eshritha
From the Department of Dermatology, S. Nijalingappa Medical College, Bagalkot, Karnataka, India
1 Department of Dermatology, Krishna Institute of Medical Sciences, Karad, Maharashtra, India E-mail: drbsankad@gmail.com
Jul-Aug 2024
19 8 2024
69 4 359361
3 2023
4 2024
Copyright: © 2024 Indian Journal of Dermatology
2024
https://creativecommons.org/licenses/by-nc-sa/4.0/ This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.
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pmcDear Editor,

Familial gigantic melanocytosis (FGM) is a rare familial disorder of pigmentation that affects males more than females. It was first described in 1984 with a term ‘familial melanopathy with gigantic melaocytes’. It presents as hyperpigmented patches with raindrop-like hypopigmented macules mainly over the sun-exposed areas.[1] Pigmentary dermatoses such as arsenic poisoning, Dowling-Degos disease (DDD), dyschromatosis universalis hereditaria (DUH) and lichen planus pigmentosus (LPP) and exogenous ochronosis (EO) look similar.[2] Distinction of these dermatoses from FGM is very essential as management is different. Dermoscopy is proven to be diagnostic tool in pigmentary conditions in the recent past. It helps in distinction of lookalike conditions. Here, dermoscopic features of FGM are described, and utility of dermoscopy in the differentiating close mimics is solicited.

A 25-year-old male patient presented with hyperpigmentation over the face and hands. He denied topical application of steroids and cosmetics. There was no history of itching, redness or photosensitivity. The patient gave similar pattern of pigmentation in his paternal aunt. On examination, there was diffuse reticulate hyperpigmentation over the face and hands along with multiple discrete hypopigmented macules [Figure 1a and b]. Multiple hypo-pigmented and hyper-pigmented macules were noted on the cheek and shoulders as well. Oral mucosa, nails and hair were normal. Systemic examination was unremarkable. DDD, DUH, LPP and EO were considered as differentials. Dermoscopy (with 10-fold magnification) of hyperpigmented lesions on the face showed brown to black and grey globules, granular brownish dots, patulous follicular openings, sebum excrescences with pinkish hue at few places [Figure 2a and b]. Pigment globules were found in skin cleavage lines too. Similar findings were noted in hand lesions also except for sebum excrescences [Figure 2c and d]. Hypopigmented lesions showed distorted pigment network with lighter shade of brown pigmentation. White dots of eccrine and follicular openings were spared in both hyperpigmented and hypopigmented areas. Histopathology revealed heavily pigmented basal layer of epidermis and numerous giant melanocytes located in basal layer. They were longer and larger than normal melanocytes. Melanophages were also observed in dermis [Figure 3a and b]. Based on clinical and histopathological features, a diagnosis of FGM was made. The patient was reassured about the benign nature of the condition.

Figure 1 Clinical image of familial gigantic melanocytosis showing reticulate hyperpigmentation on the face, hands, neck and chest (a). Close-up view showing bluish pigmentation with scattered depigmented macules (b)

Figure 2 Dermoscopy of familial gigantic melanocytosis shows patulous follicular openings (green arrows), black to brown (white circle) and grey (white arrows) globules, granular brown pigmentation (green box) (a, d, c, d). Sebum excrescences (green circles) are noted in the facial lesions (b). White macules reveal white areas with distorted pigment network (red stars). White dots of eccrine openings and follicular ostia are conspicuously spared. [DermLite 3, Polarised, 10X magnification]

Figure 3 Histopathology of familial gigantic melanocytosis shows heavily pigmented basal layer of the epidermis [H and E 10x] (a). Giant melanocytes, longer and larger than normal melanocytes were noted in the epidermis with melanophages in the dermis. [H and E 40x] (b)

Dermoscopy is a rapid, non-invasive diagnostic technique that demonstrates exclusive features in pigmentary disorders. Dermoscopy of FGM is not described in the literature. In this case, intense brown to black and grey pigment globules were scattered all over the lesions involving the skin lines. At few areas, granular brown dots were observed. Eccrine openings and follicular ostia were symbolically spared.

Dermoscopy of DDD is characterised by a comedo-like opening and star-shaped pigment structures around follicular openings and in skin cleavage lines. Macules show white areas with distorted pigment network.[3] Similar changes were noted in FGM except comedo-like openings and star-shaped pigment structures. LPP shows overlap patterns, particularly the dotted, arcuate, reticular and scattered pigment globules. Color varies from brown to grey. Skin lines and eccrine and follicular openings are spared. By contrast, skin lines were involved in FGM, and granular pigment dots are not seen in LPP.[4] EO is typified by grey-brown globules in a ‘curvilinear or worm-like’ pattern involving even follicular opening with sharply focused vessels which is not a feature of FGM. White confetti-like macules show white areas with distortion of pigment network.[4] Furthermore, none of mentioned conditions reveal sebum excrescence. Hence, dermoscopy is useful in differentiating pigmentary disorders that mimic each other clinically.

In terms of dermoscopy-histopathology correlation, brown or black pigment corresponds to melanin in larger and longer melanocytes, whereas grey globules are due to melanin or melanophages in the dermis. Sebum excrescences, noted as white spicules that emerge from follicular openings, were convincingly observed in facial lesions because of prominence of sebaceous glands in that area. However, their presence may not be characteristic of FGM. Patulous follicular openings suggest infundibular dilatation. Granularity of pigment dots could be due to melanin in normal melanocytes. Lighter brown shade in hypopigmented area is due to reduced melanin in basal layer. Pinkish hue is due to vasodilatation.

To conclude, dermoscopy in FGM demonstrates discriminative features that correlate with histopathological changes. Dermoscopy is useful in distinguishing closest clinical differentials of FGM. These are preliminary observations; further studies are recommended to validate our findings.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.
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2 Rambhia KD Chowdhary KS Rao GV Khopkar US Familial gigantic melanocytosis Indian J Dermatol Venereol Leprol 2018 84 192 4 29393076
3 Khunger N Bishnoi A Jindal A Rajan A Ankad BS Bhat YJ Rambhia KD Hyperpigmented dermatoses IADVL Atlas of Dermoscopy 1st ed New Delhi Jaypee Brothers Medical Publishers 2022 102 27
4 Vinay K Ankad BS Dermatoscopic features of pigmentary diseases in ethnic skin Indian Dermatol Online J 2021 12 24 33 33768020
