Non-autoimmune hyperthyroidism associated with isolated bilateral ocular lymphoma mimicking Graves' disease with ophthalmopathy: a cause of misdiagnosis.

A very rare association of non-autoimmune hyperthyroidism due to nodular goiter with isolated bilateral non-Hodgkin's ocular lymphoma is described. A 66-year-old woman presented with bilateral proptosis, marked periocular swelling, conjunctival hyperemia and chemosis, severe extraocular muscle impairment with diplopia. Thyroid function tests showed normal free thyroid hormone concentrations with undetectable serum thyrotropin levels. Patient was placed on antithyroid drug treatment, ocular conditions deteriorated. More than two years later, when first seen in our institution, orbital CT scan showed the presence of a retro-ocular mass that, at biopsy, proved to be B-cell non-Hodgkin's lymphoma, apparently with no localization in other sites. Thyroid evaluation revealed subclinical hyperthyroidism due to an autonomous thyroid nodule in the left lobe of the gland. Radiotherapy of the orbit was followed by a dramatic regression of lymphoma, but further staging some months later showed involvement of several abdominal lymph node structures. This case underscores the need of a thorough diagnostic work-up of ocular disease resembling Graves' ophthalmopathy, even when it is bilateral and associated with overt or subclinical hyperthyroidism.