Immunohistology of eye muscle in idiopathic orbital inflammatory disease (pseudotumor), Graves' ophthalmopathy and healthy controls.

Inflammatory orbital disease can be triggered by a variety of causes. Two such diseases are pseudotumor orbitae and Graves' ophthalmopathy, and both involve extraocular muscles. Biopsies were obtained from ocular muscles during a quiet phase in these two diseases. Biopsies obtained from a previous pseudotumor orbitae showed complement deposits and increased expression of HLA class-I antigens in the intermuscular tissue. The biopsies from two out of four pseudotumor cases and two out of four Graves' ophthalmopathy cases contained increased numbers of intermuscular HLA class-II-expressing cells. In spite of clinical remission, the local condition in all four pseudotumor cases and in two out of four cases of Graves' ophthalmopathy still suggests active inflammatory disease.