Matt, a 41-year-old electrician, presents with intermittent right arm swelling for about one month, worsening over the past few days and now with associated purple-red discolouration and pain in the hand.

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Matt, a 41-year-old electrician, presents with intermittent right arm swelling for about one month, worsening over the past few days and now with associated purple-red discolouration and pain in the hand.

There has been no associated injury, trauma, fever or systemic features. Matt is generally well, has no history of note and takes no medications. He is right handed and does a lot of work with his arms raised overhead.