Primary orbital melanoma associated with orbital melanocytosis
C. D. Rice and H. H. Brown
Department of Ophthalmology, University of Arkansas for Medical Sciences, Little Rock 72205.
We report a case of primary orbital melanoma in a 17-year-old girl. The
patient presented with painless proptosis during the first trimester of
pregnancy. Computed tomography demonstrated a well-circumscribed mass
located infra-temporally in the right orbit. The tumor was bluish-black,
grossly encapsulated, and associated with orbital blue nevi. Histologic
examination of the mass revealed a pigmented spindle-cell neoplasm. On
electron microscopy, the presence of premelanosomes and the absence of
basal lamina supported the diagnosis of melanoma. Malignant transformation
of a preexisting nevus is postulated since perineural foci of benign
dendritic melanocytes were seen within the melanoma. There has been no
recurrence or metastasis in a 2-year follow-up. Of 30 primary orbital
melanomas reviewed, 12 (40%) were associated with periorbital pigmentary
disorders, such as oculodermal melanocytosis, blue nevus, and ocular
melanocytosis. Our case is unique since the pigmentary lesions were limited
to the orbital tissues.
