Nevus of OtaD22.30

Mostly congenital dermal melanocytic nevus (also known as ocular dermal melanosis), a benign dermal melanosis that occurs mainly in the area of the trigeminal distribution. The first and second segments of the trigeminal nerve, namely the ophthalmic V1 and maxillary V2, are most frequently affected. This is often associated with melanosis of the sclera. Pigment nevus occurs almost exclusively in people of Asian descent, especially in women.

Acquired dermal melanosis has also been described in Asian women(Acquired, bilateral nevus of Ota-like macules(Yang X et al. 2023).

S.a.u. Naevus fuscocoeruleus deltoideoacromialis.

The following classification has been proposed (Huang WH et al. (2013):

• Type I (mild): Type A is periocular. Type B affects the zygomatic region. Type C affects the forehead. Type D affects only the nose.
• Type II (moderate): Similar to type I, but to a greater extent.
• Type III (intense): Periocular, nasal and scalp involvement.
• Type IV: Bilateral involvement.

The exact etiology is unknown. Various hypotheses have been put forward:

• The melanocytes do not migrate from the cells of the neural crest into the basal layer of the epidermis (foot disease of melanogenesis).
• Previous radiotherapy/radiation exposure/hormonal factors (?)
• Mutations in the BRAF and NRAS genes of the MAP kinase pathway have been suspected, as have mutations in the GNAQ gene (GNAQ stands for "G Protein Subunit Alpha Q"), a protein-coding gene located on chromosome 9q21.2.
• The monosomy of chromosome 3 and the increase of the long arm of chromosome 8q is a significant risk factor for uveal melanoma and a poor outcome (Swann PG et al. 2010)

Nevus fuscocoeruleus ophthalmomaxillaris (nevus ota) is usually asymptomatic, although loss of sensation has been reported in rare cases. It is characterized by bluish hyperpigmentation along the ophthalmic and maxillary segments (V1 and V2) of the trigeminal nerve. The nevus fuscocoeruleus ophthalmomaxillaris is usually unilateral, rarely bilateral. Morphologically, the lesions are macular (rarely papular or nodular), patchy brown, slate blue or with gray-black pigmentation, with deeper lesions appearing blue. The lesions are confluent, flat with blurred borders. The pigmentation can affect extracutaneous sites such as the eyes (conjunctiva, sclera, cornea and uvea). The oral cavity and nasal mucosa may also be affected.

Extracutaneous manifestation: involvement of the eye and buccal mucosa is possible. Up to 26% of patients show bilateral manifestations. Involvement of the tympanic membrane (55%), eyes (49%), nasal mucosa (28%), pharynx (24%) and palate (18%). Associated symptoms: glaucoma, cataract, deafness, occiput deformity, hemiatrophia facei.

A complete ophthalmologic examination should be performed, including visual acuity testing, intraocular pressure measurement, slit lamp examination of the anterior segment and dilated fundus examination. Subconjunctival melanosis and episcleral pigmentation can be easily recognized during the slit lamp examination.

A dilated peripheral retinal examination is recommended to rule out changes in the choroid, in particular a choroidal melanoma. A stereoscopic examination of the optic nerve head is recommended to document any curvature of the optic nerve head.

There is no definitive diagnostic test to confirm the nevus of Ota. The diagnosis can be made based on the clinical morphology and topographic distribution of the lesions. Dermatoscopy shows bluish to slate gray homogeneous pigmentation. A skin biopsy is required if the overlying skin develops ulceration or if there is a pigmentary change with the development of papules.

Acquired bilateral naevus Ota-like pigment spots: these are acquired, not congenital, pigmentation of the sclera is rather unlikely.

Treatment is required for cosmetic reasons or in the case of malignant transformation. Cosmetic coverage if necessary (e.g. Dermacolor). Pulsed Q-switched laser surgery is the treatment of choice for the nevi of Ota nevus. It targets the dermal melanocytes and melanophages through their selective photothermal and photomechanical destruction, thereby reducing pigmentation.

For more extensive lesions or metastases, a combination of surgical excision and radiotherapy, transpupillary thermotherapy or chemotherapy may be attempted. Chemical peels, dermabrasion, electrocautery or cryotherapy are further optional treatment methods (Alster TS et al. 1995).

A nevus fuscocoeruleus ophthalmomaxillaris is usually initially presented to ophthalmologists or dermatologists as a cosmetic problem due to the bluish discoloration of the periocular skin and sclera. It is primarily a clinical diagnosis, but there is generally an increased risk of glaucoma and choroidal melanoma (10% and 0.25% respectively). It is important to measure intraocular pressure, perform gonioscopy and indirect ophthalmoscopy at the first visit. Serial monitoring of intraocular pressure is recommended to detect early glaucoma. Close interprofessional team coordination with ophthalmologists, dermatologists and primary clinicians is indicated for the management of these patients.

The development of intracerebral melanin-forming tumors is very rare but possible.

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