Increasing incidence of ophthalmic lymphoma in Denmark from 1980 to 2005.

PURPOSE To evaluate patient characteristics and incidence of ophthalmic lymphoma in Denmark during the period 1980 to 2005. METHODS All patients in Denmark with a diagnosis of ophthalmic lymphoma during the period 1980 to 2005 were retrieved from three different population-based registries. Specimens from all patients were collected and reclassified according to the World Health Organization (WHO) classification system. Incidence rates were calculated by using Poisson regression models. RESULTS A total of 228 patients with a histologically verified diagnosis of ophthalmic lymphoma were included. There was an equal distribution of males and females. The most frequent lymphoma subtype was extranodal marginal zone B-cell lymphoma (MALT [mucosa-associated lymphoid tissue] lymphoma, 55.5%) and most cases were located in the orbit (56.8%). High-grade lymphoma subtypes were found more frequently in males than in females. Incidence rates were highly dependent on the patient's age. For all ages, a statistically significant annual average increase of 3.4% during the 26-year period was found. This increase was primarily due to a rise in the incidence of MALT lymphoma. CONCLUSIONS In the Danish population ophthalmic lymphoma consists primarily of orbital MALT lymphoma. Although it is a rare disease in mostly elderly patients, the incidence of ophthalmic lymphoma is increasing at a rapid pace.