A 77-year old male with a history of rheumatoid arthritis and myasthenia gravis on azathioprine and prednisone was admitted to the intensive care unit in respiratory distress. During his first two weeks of hospitalization, purpuric lesions developed over his left arm and a dermatology consultation were requested.

(image attached) What can be the probable diagnosis for this patient? *This case is from Docplexus editorial team for educative purpose only Source: Washington school of medicine