This is a vasculitis similar to Churg Strauss except it affects smaller blood vessels. The initial course of the illness typically affects the upper respiratory system and lungs mimicking mast cell disorders.

I have severe Reynaud's and my fingers and toes sometimes turn black which COULD be caused by granulomas blocking the small blood vessels. Because of this & my MCAD symptoms,  I am being worked up for this condition.

Here's more info on the Mayo Clinic site:

http://www.mayoclinic.com/health/wegeners-granulomatosis/DS00833

Julie