Mass on Lung

Is there a medical term for when a mass is found on a lung of a 45 yr. old that turns out to be a twin?

The mass is a twin or the 45 is a twin??? Clarify please.

The mass is a twin, I've never heard of this before and wanted to do some resherch and have no idea were to start, so I was wondering if there was a name for this condition~

there is a vanishing twin where a sono shows 2 then later there is 1 who knows where it goes. I saw on some discovery health show one where a baby boy had his twin in his stomac. It grew so far then stopped. I guess the one grew around it and the sono before he was born showed a mass.

Thanks for taking the time to explain a little~