A 48-year-old lorry driver presented with 3 weeks of blurred vision, pain and diplopia. There was a right upper lid ptosis with some restriction of eye movements. A CT revealed an enlarged lacrimal gland and lacrimal gland biopsy showed IgG4-positive plasma cells. The patient responded to oral prednisolone and fully recovered. As a condition which mimics a number of diseases, an IgG4-related disease presents a diagnostic challenge and ought to be considered in both acute and chronic presentations.