Pulmonary scarring and its relation to primary lung cancer

BACKGROUND: Lung scar carcinoma, so called ‘scarcinoma’, is a perceived entity that was originally described by Friedrich in 1939, in which a carcinoma originates from peripheral scarring of lung tissue. In a recent pilot study, there was a strong association between the geographic location of lung cancer and the presence of scarring of the lung. OBJECTIVES: To investigate this relationship in the largest cohort to date. METHODS: We reviewed all radiological images of patients (N=917) with confirmed lung cancer from 2013 - 2017 and included all who had at least a staging computed tomography (CT) of the chest and a tissue diagnosis of primary lung cancer. Two pulmonary specialists categorised all patients as no pulmonary scarring, scarring in the same lobe, scarring in the ipsilateral lung, but not lobe, scarring in the contralateral lung and diffuse scarring both lungs. RESULTS: Almost 1 in 3 patients had pulmonary scarring. In patients with lung cancer, if scarring was present, the pulmonary scarring was more likely to be found in the same lobe as the cancer compared with any other lobe, including the same lung (p<0.0001). CONCLUSION: Pulmonary scarring was common, and there was a strong association between the geographical location of scarring and primary lung cancer in those with scarring.