The findings in this case are typical for a right middle lobe infarct; however, in this case it is secondary to an endovascular calcified structure within the adjacent vessel.  This may represent a congolomerate of cutting material such as talc, but given that it is more calcified periperhally, with a central medullary cavity, it is favored to represent a phlebolith. Presumably, given the patient's history of IV drug abuse, he may have dislodged a stable phlebolith into the venous system where it was able to travel back to and through the heart to embolize the lung. Quite bizarre.

This case is courtesy of Dr. Aaron Schein of USC, who generously shared it with me.