A left lung with four lobes: a new discovery during the thoracotomy for recurrent primary spontaneous pneumothorax

Background The right and left lung anatomy are similar but asymmetrical. The right lung consists of three lobes, and the left lung consists of two lobes. Our study is unique because of discovering a very rare morphological feature of the left lung which has not been reported yet. By the way, we compared two different available chemical agents for pleurodesis (talc and bleomycin) according to side effects, complications, and pneumothorax recurrence. Case presentation We reported a case of bilateral primary spontaneous pneumothorax, who underwent talc slurry and bleomycin pleurodesis at right and left side retrospectively, and then complicate with left-sided recurrent spontaneous pneumothorax, so underwent open thoracotomy and was surprisingly and accidentally found to have 4 lobes and 3 fissures in left lung. Conclusion In our case report, there were one main oblique fissure and two accessory fissures which divided the lung into 4 separated lobes, and this discovery in human's and other animals' lung anatomy has not been previously reported. In our case study, the talc slurry was more effective in preventing spontaneous pneumothorax recurrence, but with more side effects than bleomycin. We could hypothesize that the morphological variation of the lung might affect spontaneous pneumothorax development and recurrence.