Pathological evaluation of orbital tumours in Japan: analysis of a large case series and 1379 cases reported in the Japanese literature.

PURPOSE: To review epidemiological features of orbital tumours in Japan.

METHODS: Retrospective, observational case series and systematic review. A total of 104 patients with orbital tumours collected at the authors' institution during 1983-2002 were assessed. In addition, 1379 cases from a large series of orbital tumours diagnosed by histopathological analysis that were previously published in Japanese ophthalmological journals from 1980 to 2004 were analysed.

RESULTS: After combining the current data with the previously published cases, there were a total of 1483 lesions with 47% classified as primary, 30% as secondary and 22% as inflammatory. The most common primary tumour was malignant lymphoma (12%) followed by pleomorphic adenoma (7%). Carcinomas from the lung, breast and thyroid were found to predominate among orbital metastases. Inflammatory pseudotumour had the highest lesion frequency (18%).

CONCLUSIONS: Malignant lymphoma by far was found to have the most dramatic increases within the recent reported series. Pleomorphic adenomas in Japan were found to be much more common compared with that reported for American and European studies.