Objective: We sought to assess the CT features of surgically resected large cell neuroendocrine carcinoma of the lung.
Materials and methods: The cases of all patients who underwent surgical resection for primary lung cancer in a single institution from 1993 to 2000 and who received an initial diagnosis of poorly differentiated non-small cell lung carcinoma, small cell carcinoma, carcinoid tumor, and large cell neuroendocrine carcinoma were histologically reviewed. The findings for 43 patients were histologically reclassified and confirmed as large cell neuroendocrine carcinoma. The CT scans available for 38 patients were evaluated by two observers.
Results: In the 38 patients, six central tumors and 32 peripheral tumors, with diameters ranging from 12 to 92 mm (mean +/- SD, 32 +/- 19 mm), were identified. None of the tumors had air bronchograms or calcification in the mass or nodule. Of the 19 patients with thin-section CT scans, 14 (74%) showed the tumor-lung interface as well defined and five (26%) showed the interface to be ill defined. Lobulation was identified on 15 scans (79%) and spiculation was evident on six scans (32%). On contrast-enhanced CT scans, inhomogeneously enhanced tumors appeared to be larger (51 +/- 18 mm) than homogeneously enhanced tumors (25 +/- 10 mm; p < 0.001). At histopathologic examination, gross necrosis was noted in 20 of 28 patients who had undergone contrast-enhanced CT, and the cause of inhomogeneous enhancement on CT scans was determined to be intratumoral necrosis. Multiple microscopic necroses were present in all 28 patients.
Conclusion: Large cell neuroendocrine carcinoma usually appears as a well-defined and lobulated tumor with no air bronchograms or calcification. The inhomogeneous enhancement (caused by necrosis) seen in large cell neuroendocrine carcinomas with large diameters is not necessarily apparent in small-diameter (< 33 mm) large cell neuroendocrine carcinomas, even if the tumor contains necrosis.