IgG4 ‐Related Disease: A Diagnostic Dilemma for 20 Years

ABSTRACT We report a case of IgG4‐related disease in a 65‐year‐old man who remained undiagnosed for two decades. His disease initially manifested as periorbital oedema, followed by right cheek swelling, lymphadenopathy and a widespread pruritic eruption of skin‐coloured and pale erythematous papules. IgG4 was only considered after a stroke protocol MRI of the brain demonstrated an incidental finding of characteristic orbital manifestations. This case highlights the diagnostic complexity of IgG4‐related disease and emphasises the importance of recognising its varied presentations to facilitate early diagnosis and management.