Unilateral proptosis due to orbital pseudotumor in a patient with Hashimoto's thyroiditis

A patient with unilateral proptosis and goiter is presented who initially was thought to have Graves' disease. However, the histologic appearance of the orbital tissue and the results of thyroid function and serologic studies were most consistent with the diagnoses of orbital pseudotumor and Hashimoto's thyroiditis, respectively, as the cause of these abnormalities. Two previous instances of an association between orbital pseudotumor and thyroiditis have been reported. A review of the literature shows that the ophthalmologic signs in patients with a pseudotumor superficially resemble those observed in subjects with thyroid ophthalmopathy. However, a palpable supraorbital mass is often present and biopsy of the mass usually demonstrates the heavy lymphocytic infiltration typical of this disease. Since the implications of the diagnosis of pseudotumor differ from those of Graves' disease, this entity should be considered in the differential diagnosis of the patient presenting with unilateral proptosis.