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  • Rare blue nevus can be mistaken for melanoma or melanosis

    Ocular Pathology/Oncology

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    This is the largest study to characterize the clinical features and course of blue nevus on the ocular surface.

    Study design

    This single-center, retrospective, noncomparative case series analyzed 23 tumors excised from 21 patients (57.1% men, 71.4% white) over a 16-year period. The authors describe clinical characteristics, pathologic features and clinical course. Each pathologic diagnosis was confirmed by one of 2 pathologists. Each specimen was bleached and stained with SOX10 and CD68 to confirm the diagnosis.

    Outcomes

    Most lesions occurred on the bulbar conjunctiva. Eight patients were diagnosed with melanoma or melanosis prior to surgery. However, pathology findings indicated that 90.5% of cases were simple blue nevus. No malignant transformations occurred during the average 20-month follow up.

    Blue nevus of the conjunctiva, in contrast to prior reports, occurred most frequently in older white men rather than women. Characteristics of the lesion overlap with nevocellular nevi, racial melanosis, primary acquired melanosis (PAM) and conjunctival malignant melanoma.

    Limitations

    Although the study is the largest retrospective design for blue nevi, the patient numbers are still quite limited at only 21 over 16 years. The findings have limited applicability as blue nevi of the conjunctiva is exceedingly rare. This condition was studied in a retrospective fashion and did not allow for a comparison between suspected diagnosis and confirmed pathology to test diagnostic accuracy.

    Clinical significance

    Since blue nevus can be confused for other melanocytic lesions, the authors suggest histologic confirmation is necessary for diagnosis as it is difficult to distinguish clinically alone. Pigmented lesions of the conjunctiva present a diagnostic challenge and a risk of malignant transformation. Immunohistochemistry shows positive staining of melan A, and Sox 10 amongst many pigmented lesions, however CD 68 stating is negative in these simulating pigmented lesions but is positive in blue nevi.