Individuals can also have lymphangioleiomyomatosis in the lungs, which are cysts where the normal lung tissue is gradually replaced by cysts lined by endothelial cells, which are the cells that normally line the blood vessels.
I had hoped the fluid from the cyst would be clear but there's a trace of blood in there, not enough to confirm the presence of cancer but a little too much to exclude it.
A follow-up scan of the Mot0rhead fan revealed that a benign cyst may have made him more vulnerable to brain injury than your standard heavy metal enthusiast.