Malignant melanoma of the lacrimal sac with surrounding melanosis.

Primary malignant melanomas of the lacrimal sac are extremely rare. In this report, the histologic findings of primary malignant melanoma of the lacrimal sac with surrounding melanosis are presented. Histologically, the surrounding melanosis showed radial proliferation of atypical melanocytes along the mucosal epithelium. Although we came to no firm conclusion as to whether the malignant melanoma in the present case was preceded by melanosis (radial proliferation of atypical melanocytes), to our knowledge this is the first description of lacrimal sac malignant melanoma associated with a lesion of this kind in the surrounding epithelium.