Roentgenographically occult bronchogenic squamous cell carcinoma: location in the bronchi, depth of invasion and length of axial involvement of the bronchus.Tohoku J Exp Med. 1986 Mar; 148(3):241-56.TJ
Forty patients with roentgenographically occult lung cancer underwent surgical resection. In thirty-five, cancer was detected by mass screening and in five at outpatient clinic. Bronchoscopic localization was accomplished in all cases. Serial block-sections of bronchi of all surgical specimens were prepared and examined microscopically. Forty-two lesions of bronchogenic squamous cell carcinoma were found including two of concurrent occult carcinoma. The site of tumor in the bronchi, the depth of mural invasion and the axial length of involved portion were investigated microscopically. The depth was measured with a micrometer. Fifteen lesions occurred in a subsegmental or a sub-subsegmental bronchus and 27 in a segmental or a central bronchus. Based on the depth of invasion (DI), occult bronchogenic carcinomas were classified microscopically into six categories (DI0 to DI5). Of the 42 lesions, 6 were judged as carcinoma in situ (DI0), 4 as suspicious invasion (DI1), 7 as intramucosal invasion (DI2), 17 as extramuscular invasion (DI3), 5 as extracartilaginous invasion (DI4) and 3 as extrabronchial invasion (DI5). Microscopic analysis revealed the presence of at least two types of infiltration in the bronchial wall. One was the creeping type in which carcinoma extended flatly along the superficial layers of bronchus and was presumed to stay as an occult lung cancer for a long time. The other, the penetrating type in which carcinoma extended deeply into the wall, was presumed to advance within a short period.