Editor,—Idiopathic sclerosing inflammation of the orbit (ISIO) is a rare but well described condition.1-4There is controversy as to whether it is a condition at one end of the spectrum of non-specific orbital inflammatory syndrome (pseudotumour)2 5 6 or whether it is a disease entity in its own right.1 Its aetiology is not known, although its association with systemic disease and multifocal fibrosclerotic conditions such as Reidel's thyroiditis, retroperitoneal fibrosis, mediastinal fibrosis, and idiopathic pachymeningitis suggests an immunological mechanism.2 4 5 7 An autosomal recessive inheritance is suggested by the pedigree of two offspring of a consanguineous marriage, who developed multifocal fibrosclerosis.8 Diagnosis is complicated by a wide variety of clinical features ranging from mild grittiness to a painful, fixed, blind eye.9 Often there are no features of active inflammation, and there may be aggressive local destruction of bone with invasion of adjacent structures …