Title: Ocular melanosis

{{Infobox medical condition
| name          =
| synonym       = '''Ocular melanocytosis''' or '''Melanosis oculi''' or '''Nevus of Ota'''
| image         =
| image_size    =
| alt           =
| caption       =
| pronounce     =
| specialty     = ophthalmology
| symptoms      =
| complications =
| onset         =
| duration      =
| types         =
| causes        =
| risks         =
| diagnosis     =
| differential  =
| prevention    =
| treatment     =
| medication    =
| prognosis     =
| frequency     =
| deaths        =
}}
'''Ocular melanosis''' ('''OM''') is a blue-gray and/or brown lesion of the [[conjunctiva]] 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]].&lt;ref name=&quot;:0&quot;&gt;{{Cite book|last=Salmon|first=John F. |title=Kanski's clinical ophthalmology: a systematic approach |date=2020 |isbn=978-0-7020-7713-5 |edition=Ninth |location=Edinburgh |oclc=1131846767}}&lt;/ref&gt; The disease is caused by an increase of [[melanocyte]]s in the [[iris (anatomy)|iris]], [[choroid]], and surrounding structures. Overproduction of [[pigment]] by these cells can block the [[trabecular meshwork]] through which fluid drains from the eye. The increased fluid in the eye leads to increased pressure, which can lead to [[glaucoma]]. In humans, this is sometimes known as [[pigment dispersion syndrome]].&lt;ref name=Gelatt_1999&gt;{{cite book |editor=Gelatt, Kirk N. |title=Veterinary Ophthalmology |edition=3rd |publisher=Lippincott, Williams &amp; Wilkins |year=1999 |isbn=0-683-30076-8}}&lt;/ref&gt;

== 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).&lt;ref name=&quot;:0&quot; /&gt; It is due to excess production of [[melanin]] 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.&lt;ref&gt;{{Cite journal |last1=Shields |first1=Carol L |last2=Shields |first2=Jerry A |date=January 2004 |title=Tumors of the conjunctiva and cornea |journal=Survey of Ophthalmology |language=en |volume=49 |issue=1 |pages=3–24 |doi=10.1016/j.survophthal.2003.10.008|pmid=14711437 |url=https://jdc.jefferson.edu/willsfp/106 |url-access=subscription }}&lt;/ref&gt;

== Primary Acquired Melanosis ==
[[File:Primary-acquired-melanosis.jpg|thumb|A light brown, patchy appearance of primary acquired melanosis (PAM).]]

PAM is a potentially cancerous lesion of the conjunctiva, which has a higher risk of transforming into a [[melanoma]] in white persons. Nearly 75% of all melanomas that arise from the conjunctiva have been found to have occurred in the setting of PAM.&lt;ref name=&quot;:1&quot;&gt;{{Cite journal|last1=Shields|first1=Jerry A.|last2=Shields|first2=Carol L.|last3=Mashayekhi|first3=Arman|last4=Marr|first4=Brian P.|last5=Benavides|first5=Raquel|last6=Thangappan|first6=Archana|last7=Phan|first7=Laura|last8=Eagle|first8=Ralph C.|title=Primary acquired melanosis of the conjunctiva: Experience with 311 eyes |date=December 2007|journal=Transactions of the American Ophthalmological Society|volume=105|pages=61–72|issn=0065-9533|pmc=2258121|pmid=18427595}}&lt;/ref&gt; 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 [[Neoplasm|neoplasia]] formation. However, PAM may occur without [[atypia]], 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 of Ota|nevus]], 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.&lt;ref name=&quot;:2&quot;&gt;{{Cite journal|last1=Laird|first1=Philip W.|last2=Woodward|first2=Maria A.|last3=Williams|first3=John G.|last4=Lee|first4=W. Barry|last5=Grossniklaus|first5=Hans E.|date=November 2012|title=Cystic Benign Melanosis of the Conjunctiva |journal=Cornea|volume=31|issue=11|pages=1273–1277|doi=10.1097/ICO.0b013e31823d1ec4|issn=0277-3740|pmc=3467456|pmid=23044615}}&lt;/ref&gt;

=== Diagnosis ===
* Usually unilateral, flat, patchy, pigmented area that involves the limbus (the border of the [[cornea]] and [[sclera]]) and interpalpebral (between the eyelids) conjunctiva.&lt;ref name=&quot;:2&quot; /&gt;
* Slit-lamp examination.
* [[Histopathology|Histopathological]] examination that shows intraepithelial proliferation of conjunctival epithelial melanocytes.&lt;ref name=&quot;:0&quot; /&gt;
* Features that may encourage the ophthalmologist to biopsy the lesion include, but are not limited to:&lt;ref&gt;{{Cite web|title=Primary Acquired Melanosis|url=https://www.nhsggc.org.uk/your-health/health-services/scottish-ocular-oncology-service/diagnosis-types/conjunctival-tumours/primary-acquired-melanosis/#|access-date=2021-03-10|website=NHS Greater Glasgow and Clyde}}&lt;/ref&gt;
** 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.&lt;ref name=&quot;:1&quot; /&gt;

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.&lt;ref name=&quot;:0&quot; /&gt;&lt;ref&gt;{{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}}&lt;/ref&gt;

==References==
&lt;references/&gt;

[[Category:Dog diseases]]
[[Category:Disorders of conjunctiva]]
[[Category:Eye color]]