INSPECTION
On inspection, the patient has an area of subepithelial melanosis associated with pigmentation of the lids and face in the distribution of the first and second divisions of the trigeminal nerve.
Look for; (PILOT)
Proptosis (orbital melanoma)
Iris pigmentation/melanosis/melanoma
Lens subluxation (ciliary body melanoma)
Optic disc (cupping)
Trabeculectomy (glaucoma operation)
PALPATION
On palpation of the skin, the lesion is macular; however, rarely, it may be papular or nodular, which means that the lesion is flat or only mildly palpable. However, over time, the lesions become darker and raised.
ALSO,
Check IOP, gonioscopy (angle pigmentation)
Examine the fundus for choroidal melanoma
Indirect ophthalmmoscopy or Tripple mirror exam to rule out uveal melanoma
Examine patient’s back for nevus of Ito
Examination of the palate for similar pigmented lesions
NARRATION:
QUESTIONS:
What are the types of congenital ocular melanocytosis?
COM is an uncommon condition wherein there is an increase in the number, size, and pigmentation of melanocytes in the sclera and uvea. The periocular skin, orbit, meninges, and soft palate may also be involved.
Ocular melanocytosis – it is the least common form. It is seen as multifocal slate-grey pigmentation is seen within the sclera and episclera. Conjunctival hyperpigmentation may incidentally be seen but is not the usual occurrence.
Dermal melanocytosis – it accounts for 1/3rd of the cases.
Oculodermal melanocytosis (Naevus of Ota) – It is the most common type and occurs bilaterally in 5% of cases.
What is racial predilection for Naevus of Ota?
Darker-complexioned races are more prone to develop this condition while being rare in white people. However, white individuals who develop Naevus of Ota are more likely to develop malignant melanoma associated with this condition.
What is the pathophysiology of the disease?
It is a benign mesodermal melanosis involving the distributions of the V1 and V2 nerves, with associated hyperpigmentation of the eye and its adnexa.
One hypothesis is that it is caused by the failure of migration of melanocytes from neural crest cells to their normal location within the basal layer of the epidermis
When does the lesions appear?
The Nevus of Ota typically presents at birth but can also appear in puberty or during pregnancy. It is more common in females than males, with a ratio of 5:1.
How do you differentiate between superficial and deep lesions?
The superficial lesions are patchy brown, slate-blue with grey-black pigmentation; whereas deeper lesions appear blue.
What are the ipsilateral associations of Naevus of Ota?
Iris hyperchromia - common
Iris mammillations – uncommon – tiny, regularly spaced, villiform lesions.
Fundus hyperpigmentation
Trabecular hyperpigmentation – if present, it is associated with glaucoma in about 10 percent of cases, as the invasion of melanocytes can block the drainage of aqueous, leading to elevated IOP.
Uveal melanoma – although it develops in a small minority of patients therefore long-term anterior and posterior segment review is required for these patients. 1/400 patients can develop uveal (typically choroidal) melanoma in the affected eye
What are the Risk factors for the malignant transformation of these naevi?
Risk factor development of malignant transformation include:
related cutaneous or palatal melanocytosis (especially in the temple)
scleral involvement of the superior, nasal, or temporal quadrants
choroidal melanocytosis
diffuse iris melanocytosis.
What is the risk of malignant transformation in these patinests?
These patients have a lifetime risk of 4% for development of uveal melanoma.
What other conditions have iris mammillations?
Iris mammillations may be independent having AD pattern of inheritance.
They may be seen in cases of
NF1
Congenital ocular melanocytosis
Naevus Flammeus (Port wine stain) associated with Sturge Weber Syndrome
What is the differential diagnosis of Naevus of Ota?
Ocular melanosis is differentiated based on the absence of eyelid involvement.
Naevus of Ito – This condition is differentiated by the hyperpigmentation of the neck, shoulders, axilla, and upper extremity
Nevus of Hori is a condition almost identical to Nevus of Ota, but this condition is bilateral on presentation, as opposed to the unilateral Nevus of Ota.
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