From: Rabbi Moshe Sofer
To: Unknown recipient
The Chasam Sofer rules that lung perforations found at sites with red spots or dots render the animal treif, as the discoloration indicates disease rather than benign worm activity. However, if the hole appears on a visually healthy part of the lung and worms are present on its surface, the animal may be permitted, as the perforation can be attributed to post-mortem worm migration. This distinction rests on the Shach's principle that the lung's constant fluttering during life prevents worms from boring through, combined with the Ran's view that lung perforations are inherently only doubtfully treif.
Source: Shu"t Chasam Sofer YD §44