Malignant melanoma of the rectum presenting as orbital metastasis.

An orbital mass being the presenting sign of disseminated systemic metastasis is a rare clinical picture. Here, the authors describe the case of a 52-year old Asian-Indian female who presented with unilateral proptosis and motility restriction. Imaging showed an irregular orbital mass infiltrating the right lateral rectus and with a significant intraconal component. Incisional biopsy helped to diagnose a malignant melanoma and exhaustive systemic imaging showed that the primary was found to be arising from the rectum. This represents the first reported case of malignant melanoma of the rectum metastasizing to the orbit and presenting with proptosis and reduced vision.