Naevus of Ota associated with segmental vitiligo: a case report

An update on ophthalmological perspectives in oculodermal melanocytosis (Nevus of Ota)

PURPOSE

To provide a review of the literature on oculodermal melanocytosis (ODM) with a focus on the diagnostic and therapeutic implications of multimodal imaging techniques in the management of ophthalmic complications.

METHODS

The authors carried out a literature search on PubMed, Medline, and Scopus of English language articles published on ODM through August 2021. This review presents traditional and novel diagnostic methods in the diagnosis and follow-up of patients with particular emphasis on addressing the role of imaging in the management of the ophthalmic complications of the condition towards improving current practice patterns.

RESULTS

ODM is a rare, prevalently unilateral, congenital condition that presents with brown or blue/gray flat asymptomatic lesions of the skin, mucosae, episclera/sclera, and uvea localized within the territory of distribution of the ophthalmic and mandibular branches of the trigeminal nerve. Glaucoma and predisposition to uveal melanoma are the main ophthalmic complications. Diagnosis and management are through comprehensive opthalmological examination and traditional imaging methods such as ultrasonography and fluorescein/indocyanine green angiography as pigmentation of the fundus can conceal subtle retinal and choroidal alterations. Anterior segment optical coherence tomography and ultrasound biomicroscopy are used to evaluate the anterior segment and the ciliary body in the presence of glaucoma or melanoma of the anterior uveal tract. Fundus autofluorescence and retinal pigment epithelium (RPE) alterations are of aid in the differential diagnosis between choroidal nevi and melanoma. Enhanced depth imaging spectral domain optical coherence tomography offers outstanding in vivo evaluation of the dimensions and details of tumors or nevi and surrounding choroidal tissues and small choroidal melanomas may show distortions of the retinal and sub-retinal profile, presence of intra and sub-retinal fluid, abnormalities of the RPE, and compression of the choriocapillaris.

CONCLUSIONS

Novel multimodal imaging techniques are significant in the diagnosis and management of the ophthalmic complications of ODM. Fundus autofluorescence and enhanced depth spectral domain optical coherence tomography have adjunctive value in the detection of early-stage melanoma and differential diagnosis between nevi and melanoma. Awareness of current and emerging imaging techniques can propagate improved standardized definition and assessment of the complications of ODM.

Autoimmunity in Segmental Vitiligo

The autoimmune basis of segmental vitiligo (SV) has only recently been recognized. Systemic autoimmune diseases are less frequently associated compared to non-segmental vitiligo (NSV), but localized skin disorders - in particular linear morphea - have been repeatedly observed in patients with SV. The inflammatory response is documented on a clinical level with cases displaying erythematous borders or a hypochromic stage, on a histopathological level with predominantly CD8 lymphocytes migrating toward the basal layer and by flow cytometry demonstrating the antimelanocyte specificity of these cytotoxic T cells. The increased risk for halo naevi and NSV in these patients further underline the immune-mediated mechanisms of SV. Nonetheless, the localized and unique distribution pattern points to somatic mosaicism. This places SV in a category of similar diseases such as lichen striatus, blaschkitis, linear lupus erythematosus, and linear scleroderma where an immune reaction against genetically mutated skin cells is believed to be the underlying cause. All these disorders are characterized by a young age of onset, a temporary disease activity with spontaneous resolution, limited response to treatment, and often long-term sequelae. Although challenging, genetic research proving this genetic mosaicism could offer crucial insights into the pathogenesis of both segmental and non-segmental vitiligo.

[Vitiligo occurring on dermal melanocytosis (nevus of Ota) in a dark-skinned patient]

BACKGROUND

Nevus of Ota is a rare disease most frequently found in Asians. It presents clinically as a bluish gray hyperpigmentation of one side of the face. Transformation into melanoma and glaucoma are the main risks. The appearance of vitiligo lesions with poliosis within a nevus of Ota is exceptional.

PATIENTS AND METHODS

A 22-year-old female patient with a nevus of Ota consulted for depigmentation of the eyelashes. Physical examination revealed hyperpigmentation in the right orbitofrontal part of her face, achromic macules and eyelash poliosis. A diagnosis was made of vitiligo developing on a nevus of Ota. Ophthalmologic examination showed hyperpigmentation of the sclera. Regular dermatologic and ophthalmologic follow-up was instituted.

DISCUSSION

Vitiligo is a condition characterized by the development of depigmented lesions secondary to chronic degradation of the melanocytes of the epidermis and the follicles. Its occurrence on congenital nevus and melanoma has already been reported. However, its appearance in dermal melanocytosis is very rare. Since the first observation of this association in 1979, only 4 other cases have been reported. The pathogenic mechanisms of this association are still poorly understood. Histopathological examination generally shows a loss of epidermal melanocytes, especially in the basal layer, while dermal melanocytes remain unaffected. In this context, vitiligo developed on dermal melanosis appears to result from the difference between the properties of normal (epidermal) melanocytes and ectopic (dermal) melanocytes.

CONCLUSION

Association of vitiligo with nevus of Ota is rare. Herein, we report a new case in a dark-skinned subject.

Two Cases of Vitiligo Developed on the Persisting Dermal Melanocytosis: Is There a Difference between Epidermal Melanocytes and Dermal Melanocytes?

Vitiligo is one of the most common pigmentary skin disorders; it is characterized by circumscribed depigmented macules due to the destruction of melanocytes. Although the etiology of vitiligo has not been fully elucidated, multiple factors including autoimmune and oxidative stress have been implicated in the pathogenesis of vitiligo. In contrast, dermal melanocytosis is histologically characterized by the presence of dermal melanocytes. It has been described that there are ectopic dermal melanocytes, which have failed to reach their proper location. A literature search revealed very few reports of patients with vitiligo developing vitiligo within dermal melanocytosis. Here, we report two cases of patients with vitiligo that occurred at pre-existing sites of dermal pigmented lesions. The histopathology showed the loss of epidermal melanocytes in spite of the existence of melanocytes in the dermis. There was no significant infiltration of inflammatory cells in the dermis. These cases illustrate unknown environmental factors as well as heterogeneity.

Glial versus melanocyte cell fate choice: Schwann cell precursors as a cellular origin of melanocytes

Melanocytes and Schwann cells are derived from the multipotent population of neural crest cells. Although both cell types were thought to be generated through completely distinct pathways and molecular processes, a recent study has revealed that these different cell types are intimately interconnected far beyond previously postulated limits in that they share a common post-neural crest progenitor, i.e. the Schwann cell precursor. This finding raises interesting questions about the lineage relationships of hitherto unrelated cell types such as melanocytes and Schwann cells, and may provide clinical insights into mechanisms of pigmentation disorders and for cancer involving Schwann cells and melanocytes.