Chullin 48 - Defects in the Lungs
Ulla said in the name of Rabbi Yochanan, "If the insides of the lung have dissolved to the point that they pour back and forth in the encasing membranes, like water in a jug, the animal is still kosher." Rabbi Abba challenged this from the following rule. We learned in the eighteen basic cases of terefah that if a lung was punctured or is deficient, the animal is terefah. Does "deficient" not include the case of Ulla? - Ulla answers, "No! Punctured means a hole that leaves all the material in place, and deficient means some material is missing around the hole. Still, this rule is talking about external deficiencies, and not about internal ones."
What if a needle was found in the lung? Some say that it probably entered there through the digestive tract, must have perforated the lung at some point, and is therefore a terefah, since such punctures never properly heal. However, others say that, although less likely, it entered through the trachea, never perforated the lung, and the animal is therefore kosher. They also assume that the minor deterioration in the vicinity of the needle is not significant.
Art: Louis Coulon - The Prick Of The Needle