Pulmonary scar cancer. A pathologic reappraisal

Area of Science:

• Pulmonology
• Oncology
• Pathology

Background:

• The term "scar cancer" has been historically used to describe lung tumors with a specific gross appearance.
• The etiology and pathological basis of this appearance require clarification.

Purpose of the Study:

• To investigate the pathological basis of the gross appearance described as "scar cancer" in lung neoplasms.
• To determine the relationship between "scar cancer" and conditions like tuberculosis or infarcts.

Main Methods:

• Prospective collection of 49 lung cancer specimens (surgical resection or autopsy).
• Gross examination of tumors for "scar cancer" features (pleural puckering, central pigmentation).
• Histopathological analysis including elastic stains to evaluate lung tissue and desmoplastic reactions.

Main Results:

• 22 of 49 tumors exhibited "scar cancer" characteristics.
• Elastic stains revealed collapsed, unfibrosed lung tissue at the center of "scar cancers," suggesting atelectasis.
• No significant desmoplastic reaction was observed in "scar cancers."
• Localized pulmonary atelectasis, secondary to small airway obstruction by tumor, was identified as the cause of the "scarred" appearance.

Conclusions:

• The term "scar cancer" is inappropriate as the appearance is due to atelectasis, not pre-existing fibrous scarring.
• Localized atelectasis caused by tumor-induced airway obstruction is responsible for the characteristic pleural puckering and central pigmentation.
• Association with tuberculosis in these cases is likely incidental.