Conjunctival Melanoma

Conjunctival Melanoma Presenting as Pigmented PatchClinical image shows an expansile pigmented patch image at the limbus image and adjacent to the iris image. Bulbar conjunctiva close to the limbus is the most common location for primary acquired melanosis (PAM).

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Scanning Magnification of PAM With AtypiaScanning magnification of this conjunctival shave biopsy shows a lentiginous basilar proliferation image that stands out even at the this power. The radial extension appears to be extensive.
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Higher Magnification of PAM With AtypiaHigher magnification of the same case confirms that atypical melanocytes image have replaced the basilar keratinocytes in the conjunctiva. There is some pagetoid upward scatter of melanocytes image.
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Higher Magnification Shows Nuclear Hyperchromasia and PleomorphismHigh-power magnification shows poorly nested proliferation of atypical melanocytes in the same lesion of PAM with atypia. The upward scatter image, nuclear hyperchromasia image, and nuclear pleomorphism resembles cutaneous melanoma in situ.

TERMINOLOGY

Abbreviations

• Conjunctival melanoma (CM)

Synonyms

• Conjunctival malignant melanoma

Definitions

• Malignant proliferation of conjunctival melanocytes commonly associated with primary acquired melanosis (PAM) with atypia

CLINICAL ISSUES

Epidemiology

• Incidence
image Rare; accounts for only 2-3% of ocular cancers
image Accounts for 1% of noncutaneous malignant melanoma
• Age
image More common in older individuals (mean age at presentation: 50-60 years)
image Exceedingly rare in children younger than 15 years of age (only 28 reported cases)

Presentation

• Asymptomatic raised, pigmented plaque, macule, or tumor
• Can range in size from millimeters to large tumor masses
• Bulbar conjunctiva close to limbus is most common location

Natural History

• Majority of cases (53-75%) arise in setting of PAM with atypia
• Remainder (18-30%) arise de novo
• Minority of cases (5%) are associated with preexisting melanocytic nevus

Treatment

• Options, risks, complications
image Avoiding manipulation of tumor during surgery reduces local recurrence rate and lymphatic spread
• Surgical approaches
image All should be completely excised with 2- to 3-mm tumor-free margins
image Sentinel lymph node biopsy recommended for high-risk tumors
– > 10 mm in diameter and > 2 mm in thickness
– Nonlimbus locations
• Adjuvant therapy
image Risk of recurrence is reduced with adjuvant cryotherapy, irradiation, or topical chemotherapy

Prognosis

• Conjunctival melanoma arising in association with PAM has higher risk of local recurrence
• 5-year survival rate: 87-95%
• 10-year survival rate: 70-86%
• After 10 years, 50% of tumors will recur locally and about 25% will metastasize
• Adverse clinical prognostic indicators include
image Nonbulbar (fornix, palpebral) location
image Involvement of lymphatics-rich caruncle

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Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Conjunctival Melanoma

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