88 Chapter 6 Results Clinicopathologic Characteristics Forty-four resection specimens were included in this study. Twenty-six patients (59%) were male and 18 female (41%). The mean age of the patients was 65.7 (range: 45 to 85 y). Sixteen patients underwent a surgical lobectomy, of which 11 were freshly cut and 5 after formalin xation; there were 21 video-assisted thoracoscopic surgery (VATS) lobectomy procedures, 6 freshly cut and 15 after formalin xation; 3 pneumonectomies, 2 freshly cut and 1 after formalin xation; and 4 segmentectomies, 3 freshly cut and 1 after formalin xation. Forty-three cases consisted of primary lung carcinomas; 26 adenocarcinomas (AdC), 13 squamous cell carcinomas (SqCC), 2 large cell carcinomas, and 2 large cell neuroendocrine carcinomas. The remaining case was a segmentectomy with metastatic colonic AdC. AdC subtyping according to the WHO classi cation of lung tumors yielded 14 acinar predominant, 4 micropapillary predominant, 3 solid predominant, 2 lepidic predominant, 1 papillary predominant, as well as 1 invasive mucinous AdC and 1 AdC in situ. Six cases had a pure growth pattern; acinar in 2, solid in 2, mucinous in 1 and AdC in situ in 1. The other 20 cases had a secondary growth pattern; acinar in 6, micropapillary in 5, solid in 4, lepidic in 3, papillary in 2. Twelve of the 26 AdC had at least minor micropapillary patterns. Loose Tissue Fragments Loose tissue fragments were detected in at least one tissue block in 32 of the 44 cases (73%) with an even distribution with regard to the participating institutions. Displaced clusters of malignant cells (malignant loose fragments) were identi ed in 31 of those 32 cases; 244 x10 elds with malignant loose fragments were identi ed in the 176 histologic sections. Twenty-seven elds with displaced benign tissue fragments (benign loose fragments) were also identi ed in the 176 histologic sections. Histologic Localization of Loose Fragments In 30 of the 31 cases with malignant loose fragments, the histologic localization was intra-alveolar (Fig. 3). In the remaining case the loose fragments were on the pleural surface. Intravascular (n = 3), pleural (n = 2), and/or luminal intrabronchial (n = 1) malignant loose fragments were also noted in the 31 cases with intra-alveolar lesions. All benign loose fragments were intra-alveolar and consisted of respiratory (bronchiolar) epithelium (Fig. 4).
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