[Idiopathic orbital inflammatory syndrome (orbital pseudotumors): diagnosis and therapy]

Pseudotumors of the orbit comprise a group of idiopathic inflammatory processes and are, except for endocrine orbitopathy, the most common reason for exophthalmos in adults. Orbital pseudotumors, also called idiopathic orbital inflammatory syndrome (IOIS), can be determined from orbital involvement in systemic fibrosing diseases. Finding the correct diagnosis can be challenging. Due to the topographic relations of the orbit to neighbouring structures, a multidisciplinary cooperation is highly recommended.

We report a case of a 42-year-old woman with unilateral exophthalmos. Additionally we found impaired motility of the affected bulbus, ptosis and reduction of visual acuity. Orbital MR imaging demonstrated dense fibrotic masses filling the whole orbita including the extraocular muscles as well as the optic nerve. Tissue specimens were extracted while performing orbital decompression via a lateral orbitotomy. Histological examination revealed a lymphatic infiltration and fibrotically destroyed tissue containing the lacrimal gland. After surgical decompression, oral steroid therapy and immunotherapy, a recovery of the visual loss could be seen.

Intraorbital fibrosclerosing pseudotumors often require a difficult long-term treatment. Therapeutic options are steroid therapy, immunotherapy, radiotherapy and surgery. The diagnostic steps include blood tests, ultrasound, CT and/or MRI as well as histological differentiation. Solid tumors and orbital involvement in diseases of the hematopoetic system have to be excluded. Since intraorbital fibrosis can be accompanied by manifestations in various other organs, a complete investigation of the body and thorough follow up are crucial.