Ocular melanosis (OM) is a blue-gray and/or brown lesion of the

conjunctiva The conjunctiva is a thin mucous membrane that lines the inside of the eyelids and covers the sclera (the white of the eye). It is composed of non-keratinized, stratified squamous epithelium with goblet cells, stratified columnar epithelium ...

that can be separated into benign conjunctival epithelial melanosis (BCEM) and primary acquired melanosis (PAM), of which the latter is considered a risk factor for

uveal melanoma Uveal melanoma is a type of eye cancer in the uvea of the eye. It is traditionally classed as originating in the Iris (anatomy), iris, choroid, and ciliary body, but can also be divided into class I (low metastatic risk) and class II (high metasta ...

. The disease is caused by an increase of

melanocyte Melanocytes are melanin-producing neural crest-derived cells located in the bottom layer (the stratum basale) of the skin's epidermis, the middle layer of the eye (the uvea), the inner ear, vaginal epithelium, meninges, bones, and heart. ...

s in the

iris Iris most often refers to: *Iris (anatomy), part of the eye *Iris (mythology), a Greek goddess * ''Iris'' (plant), a genus of flowering plants * Iris (color), an ambiguous color term Iris or IRIS may also refer to: Arts and media Fictional ent ...

, choroid, and surrounding structures. Overproduction of

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compo ...

by these cells can block the

trabecular meshwork The trabecular meshwork is an area of tissue in the eye located around the base of the cornea, near the ciliary body, and is responsible for draining the aqueous humor from the eye via the anterior chamber (the chamber on the front of the ...

through which fluid drains from the eye. The increased fluid in the eye leads to increased pressure, which can lead to

glaucoma Glaucoma is a group of eye diseases that result in damage to the optic nerve (or retina) and cause vision loss. The most common type is open-angle (wide angle, chronic simple) glaucoma, in which the drainage angle for fluid within the eye rem ...

. In humans, this is sometimes known as

pigment dispersion syndrome Pigment dispersion syndrome (PDS) is an eye disorder that can lead to a form of glaucoma known as pigmentary glaucoma. It takes place when pigment cells slough off from the back of the iris and float around in the aqueous humor. Over time, these ...

Benign Conjunctival Epithelial Melanosis

BCEM, also referred to as conjunctival hypermelanosis, complexion-associated melanosis, or racial melanosis, is a non-cancerous lesion of the conjunctiva that is more commonly found in dark-skinned individuals (over 90% of lesions are found in black persons and around 5% in white persons). It is due to excess production of

melanin Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino ...

in the setting of a normal number of melanocytes in the conjunctiva. It appears very early in life and the pattern does not seem to change upon reaching adulthood. There can be asymmetrical involvement of the eyes, and lesions are usually described as flat, brown, and patchy areas of pigmentation.

Primary Acquired Melanosis

PAM is a potentially cancerous lesion of the conjunctiva, which has a higher risk of transforming into a

malignant melanoma Melanoma, also redundantly known as malignant melanoma, is a type of skin cancer that develops from the Biological pigment, pigment-producing cells known as melanocytes. Melanomas typically occur in the skin, but may rarely occur in the mouth, i ...

in white persons. Nearly 75% of all melanomas that arise from the conjunctiva have been found to have occurred in the setting of PAM. It is different from BCEM because there is a proliferation, or an increase in the number of melanocytes, which is attributed to greater risk of

neoplasia A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

formation. However, PAM may occur without

atypia Atypia (from Greek, ''a'' + ''typos'', without type; a condition of being irregular or nonstandard) is a histopathologic term for a structural abnormality in a cell, i.e. it is used to describe atypical cells. Atypia can be caused by an infection ...

, which has no risk of malignant transformation, or with atypia. It is very important to determine at which age the lesion was first noticed because it is more likely to be a benign

nevus Nevus (plural nevi) is a nonspecific medical term for a visible, circumscribed, chronic lesion of the skin or mucosa. The term originates from ''nævus'', which is Latin for "birthmark"; however, a nevus can be either congenital (present at bir ...

, or mole, the earlier it is found. It may appear similar to BCEM since the lesion may also be flat, brown or blue-gray, and diffuse throughout the conjunctiva, but it is almost always only found on one eye.

Diagnosis

* Usually unilateral, flat, patchy, pigmented area that involves the limbus (the border of the

cornea The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power ...

and sclera) and interpalpebral (between the eyelids) conjunctiva. * Slit-lamp examination. *

Histopathological Histopathology (compound of three Greek words: ''histos'' "tissue", πάθος ''pathos'' "suffering", and -λογία ''-logia'' "study of") refers to the microscopic examination of tissue in order to study the manifestations of disease. Spec ...

examination that shows intraepithelial proliferation of conjunctival epithelial melanocytes. * Features that may encourage the ophthalmologist to biopsy the lesion include, but are not limited to: ** Increasing size or size greater than 5mm ** Involvement of conjunctiva underneath the eyelids ** Nodular appearance ** Appearance of blood vessels surrounding the patch ** Previous history of melanoma

Treatment

There are a few management and treatment strategies for PAM. When lesions are small, they can be carefully watched on an annual basis. It is important to compare pictures year to year. However, for medium and large-sized lesions, we can consider surgery (excisional vs incisional biopsy), chemotherapy, or cryotherapy. When a patient has PAM with atypia, an excisional biopsy with cryotherapy is recommended as the treatment. For some patients with diffuse lesions, surgery is not an option. In these cases, the recommendation is cryotherapy in combination with topical mitomycin C, which is a chemotherapeutic agent.{{Cite web, date=2013-09-01, title=Conjunctival Pigmented Lesions: Diagnosis and Management, url=https://www.aao.org/eyenet/article/conjunctival-pigmented-lesions-diagnosis-managemen, access-date=2021-03-10, website=American Academy of Ophthalmology, language=en

References

Dog diseases Disorders of conjunctiva Eye color