The Rotten Lung
Scholars have said that seeing a rotten lung in a dream might indicate the approach of one's demise, as the lung is the seat of the soul. It was also mentioned that back pain could signify the death of a brother or someone through whom the dreamer gains strength, such as a child, leader, or friend.
Per Ibn Sirin's Muntakhab al-Kalam fi Tafsir al-Ahlam
Note: These are traditional scholarly interpretations (ijtihad) drawn from a specific classical source — not a binding religious ruling, fortune-telling, or a prediction of the future.