Accessory Fissure Of Right Lung: A Report Of Two Cases.

Right lung is divided into upper (superior), middle and lower (Inferior) lobes by an oblique and a horizontal fissure.Oblique fissure passes spirally from posterior border to inferior border deep into the lung separating the lower lobe from upper and middle lobes. A short horizontal fissure passes horizontally forwards from the oblique fissure at midaxillary line to meet the anterior border at 4th costochondral junction. This separates the upper lobe from the middle lobe. During routine dissection in 2010-11 undergraduate batch, we came across two cases of right lungs where an accessory fissure was extending horizontally backwards from the oblique fissure at mid axillary line towards the vertebral part of medial surface. In the 1st case, this accessory fissure was not meeting the normal horizontal fissure where as in the 2nd case it was meeting. This accessory fissure separates the lower lobe into a superior and an inferior segment. Knowledge of different types of accessory fissures is important because it may mislead the radiological findings, may act as a barrier to spread of infection creating a sharply marginated pneumonia which can wrongly be interpretated as atelectasis or consolidation. Identification of completeness of fissure is important prior to lobectomy, because individuals with incomplete fissures are more prone to develop postoperative air leak. Considering the clinical importance of such anomalies, anatomical knowledge and prior awareness of accessory fissures in the lungs may be important for clinicians and radiologists.