AUTHOR=Rose Anna M. , Luthert Philip J. , Jayasena Channa N. , Verity David H. , Rose Geoffrey E. 

TITLE=Primary Orbital Melanoma: Presentation, Treatment, and Long-term Outcomes for 13 Patients

JOURNAL=Frontiers in Oncology

VOLUME=Volume 7 - 2017

YEAR=2017

URL=https://www.frontiersin.org/journals/oncology/articles/10.3389/fonc.2017.00316

DOI=10.3389/fonc.2017.00316

ISSN=2234-943X

ABSTRACT=BACKGROUND: Periocular melanoma is a rare but often deadly malignancy that arises in the uvea (commonest origin), conjunctiva or orbit (rarest primary site).  Melanoma accounts for 5-10% of metastatic/secondary orbital malignancies, but only a tiny proportion of primary orbital neoplasia. Primary orbital melanoma (POM) is exceedingly rare, with approximately 50 cases reported to date. 
METHODS: All patients seen in the orbital unit at a tertiary referral hospital (1991-2016) with a biopsy-proven diagnosis of POM were identified from a diagnostic database and were studied. The case notes, imaging, surgical approach and histology were reviewed. 
RESULTS: Thirteen patients (5 male; 38%) presented with isolated malignant melanoma of the orbit, for which no other primary site was identified at presentation or during an average follow-up of 44 months (median 22; range 0 – 13 years).  The patients presented between the ages of 40 and 84 years (mean 55.5; median 48 years) and typically gave a short history of rapidly increasing proptosis and eyelid swelling.  On the basis of history, a malignant lesion was suspected in most patients and all underwent incisional biopsy, with debulking of the mass in 10 (77%) patients, and skin-sparing exenteration in 3/13 (23%).  Ten patients underwent orbital radiotherapy and the survival to date ranged from 9 months to 14 years (mean 55 months; median 23 months); two patients received solely palliative care for widespread disease and one patient refused orbital radiotherapy.  Five of the 13 (38%) patients died from the disease. 
DISCUSSION: Primary orbital melanoma is a very rare malignancy, but clinical analysis of this cohort gives insight into disease presentation and prognosis.  The tumour typically presents with a rapidly-progressive, well-defined mass that is, in some cases, amenable to macroscopically-intact excision.  Unusual for malignant melanoma, some of these patients can show an unusually long period of quiescent disease after surgical debulking and radiotherapy.