Explain the differences between polymyositis, systemic necrotizing vasculitis, polymyalgia rheumatica, ankylosing spondylitis, Reiter’s syndrome, and Sjorgen’s syndrome.

 Explain the differences between polymyositis, systemic necrotizing vasculitis, polymyalgia rheumatica, ankylosing spondylitis, Reiter’s syndrome, and Sjorgen’s syndrome.