Blue vitiligo: dermoscopic analysis and review of literature

Sir, A 45-year-old woman presented to dermatology out patient department with a 4-year history of gradually progressive asymptomatic whitish lesions over abdomen, upper and lower limbs. She denied taking any treatment for it in the past apart from applying bel patthar (Wood apple) 15 days back, which led to the bluish discoloration of the lesions. On examination, there were multiple depigmented macules having a bluish tinge peripherally over the inframammary area, dorsum of hand, left forearm, and lower abdomen [Figure 1]. Dermoscopy of these depigmented macules with bluish-tinge revealed whitish areas with the absence of the reticular pigmentary network and the presence of multiple gray to brownish dots and globules arranged in a linear, speckled, and semicircular pattern [Figure 2A and B]. Skin biopsy revealed decreased melanocytes in the epidermis with pigment incontinence, melanophages, and perivascular lymphocytic infiltrate present in the upper dermis [Figure 2C]. On correlating clinical, dermoscopic, and histopathological findings, we diagnosed it as a case of blue vitiligo. The patient was advised to apply mometasone furoate 0.1% cream.Figure 1: Clinical image of blue vitiligo showing depigmented macules with bluish hue at the periphery.Figure 2: (A and B) White structureless areas with the absence of reticular pigmentary network (black star) and the presence of multiple gray to brownish dots and globules arranged in a linear (black solid arrows), speckled (black triangle), and semicircular pattern (red arrows). (C) Histopathology showing the absence of melanin in the epidermis and the presence of melanophages with the upper dermal mild to moderate lympho-histiocytic inflammatory infiltrate.Blue vitiligo was first reported in 1994 by Ivker et al.[1] in a person with rapidly progressive vitiligo who had developed psoriasiform dermatitis after the Psoralen Ultraviolet A (PUVA) photochemotherapy. These psoriasiform plaques resolved with post-inflammatory hyperpigmentation. Eventual development of vitiligo lesions over these pigmented areas appeared as bluish tinged depigmented macules. Therefore, it was hypothesized that the pigmentary incontinence in dermis appeared blue through the depigmented areas due to the Tyndall effect. There are other reports in literature where blue vitiligo developed de novo.[2‐4] Dermoscopic features of blue vitiligo reported in the past have shown white structureless areas with multiple blue-gray dots that can be arranged in an arcuate, linear, semicircular, and speckled pattern.[2‐4] Presence of reticular telangiectasis has also been reported in one case report.[5] Similarly, in our case, we were able to see these blue-gray dots in the depigmented white patches with the absence the reticular network of normal pigmented skin. However, telengectasias were not observed. Blue vitiligo can closely mimic other conditions like lichen sclerosus, discoid lupus erythematosus, and lichen planus pigmentosus, both clinically and dermoscopically. However, the presence of certain other features can help in distinguishing these conditions from blue vitiligo [Table 1]. Table 1 - Dermoscopic features of close mimickers of blue vitiligo Condition Dermoscopic features Blue vitiligo[2‐4] White structureless areas with the absence of a normal pigment network Blue-gray dots and globules arranged in a linear, arcuate, semicircular, and speckled pattern within depigmented patches +/– Telengectasias Lichen sclerosus[6] White-yellow structureless areas Blue-gray dots Linear irregular vessels Keratotic plugs Perifollicular scaling Rosettes Discoid lupus erythematosus[7] Follicular keratotic plug Perifollicular whitish halo Blue-gray and brown dots Telangiectasia Follicular red dots White rosettes White areas Lichen planus pigmentosus[8] Blue-black to gray dots in various patterns (hem-like, linear, arcuate, and nonspecific/peppering) Perieccrine and perifollicular dots and globules The etiology for the development of blue vitiligo is still not clear, with some authors proposing the cause of dermal pigmentation to be an exaggerated lichenoid reaction and others hypothesizing it to be due to the deposition of drugs or due to a secondary insult causing the proliferation of dermal melanocytes (phototherapy). In our patient, there was history of application of bel patthar (Wood apple) leaves/pulp to the lesion. A literature review revealed that dye extracted from Wood apple leaves is being explored as a potential photosensitizer in making solar cells.[9] Therefore, in our case, we hypothesized that the application might have resulted in the development of these blue vitiligo lesions. Further studies are warranted to find out the cause for this rare variant of vitiligo. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.