Thank your for your reply, Mrs D. The Doctors and I have considered many other differential diagnoses but HAE was not one of them. I can see why you might suggest this although I don't think that I have any other features of this condition. Also, the pain of these attacks on my knees tends to start as a small, acutely painful red patch on the margin of my kneecap with associated stiffness which rapidly spreads to encompass the entire knee with diffuse swelling. I had attributed the greater occurrence during April-Sept to photo-sensitivity. I get low grade fever, malaise, fatigue, pleuritic pain etc too.

I was investigated extensively in 2013 by an internationally recognised Professor of Rheumatology (Lupus) with some immunology blood tests, PFT's, SFEMG etc with no glaringly obvious diagnosis other than SLE/UCTD to explain the clinical symptoms. After 25 years of this and now feeling old, I don't have the resilience and gritted determination to push through the disabling pain of these recurrent events in the way that I used to. My Rheumatologist (I no longer see the Prof) reassures himself that the Mycophenolate is doing its job well but sometimes I wonder hence my question about possible Enthesitis as part of an SpA where the treatment might be different.

Can I ask if you had other symptoms of the HAE other than a swollen knee?

Many thanks again. Clare