Primary orbital melanoma in association with cellular blue nevus.

PURPOSE To describe 3 cases of primary orbital melanoma associated with either known or subsequently discovered cellular blue nevus. METHODS The clinical records and surgical specimens of 3 patients who underwent orbital exenteration for primary orbital melanoma and who had a cellular blue nevus diagnosed before or after detection of the melanoma were retrospectively reviewed. RESULTS All 3 patients presented with signs and symptoms of an orbital mass. Subsequent biopsy revealed invasive melanoma. One patient had a known history of congenital cellular blue nevus of the eyelid from which the orbital melanoma originated. The other 2 patients had no known history of cutaneous pigmentation or blue nevus. In these 2 patients, the cellular blue nevus was detected on pathologic review of the orbital exenteration specimen (1 patient) or surgical biopsy specimen (1 patient). All 3 patients underwent total body positron emission tomography/computed tomography, and in all 3 results were negative for other sites of disease involvement. In the 2 patients without a previously known nevus a total body skin check was negative for other primary melanoma lesions. All 3 patients underwent orbital exenteration followed by postoperative radiation therapy. CONCLUSIONS Thorough evaluation of biopsy specimens of "primary" orbital melanoma is warranted to ensure identification of any associated blue nevus because blue nevi are precursor lesions for orbital melanoma, and the presence of a blue nevus would support a primary orbital melanoma rather than a metastatic lesion. Patients with a known blue nevus of the periocular skin and ocular adnexa should be monitored closely for signs of malignant transformation.