665 Atypical Carcinoid of the Lung: Radiographic Features R. H. Choplin1 E. H. Kawamoto2 R. B. Dyer1 K. R. Geisinger2 S. E. Mills3 T. L. Pope4 Received August 6, 1985; accepted after revi- sion December 12, 1985. Presented at the annual meeting of the American Roentgen Ray Society, Boston, April 1985. K. R. Geisinger is a Junior Faculty Clinical Fellow of the American Cancer Society. 1 Department of Radiology. Wake Forest Univer- sity Medical Center, 300 Hawthorne Rd., Winston- Salem, NC 27103. Address reprint requests to R. H. Choplin. 2 Department of Pathology, Wake Forest Univer- sity Medical Center, Winston-Salem, NC 27103. of Pathology, University of Virginia Medical Center, Charlottesville, VA 22908. Department of Radiology, University of Virginia Medical Center, Charlottesville, VA 22908. AJR 146:665-668, April 1986 0361 -803x/86/1 464-0665 © Amencan Roentgen Ray Society Atypical carcinoid of the lung is a neuroendocnne neoplasm with cellular and clinical features intermediate between those of typical carcinoid and small cell undifferentiated carcinoma of the lung. These neoplasms exhibit a wide range of histologic appearances and are misdiagnosed in up to 50% of cases. The clinical records and radiographs of 32 patients with this diagnosis from the University of Virginia Medical Center and Wake Forest University Medical Center were reviewed. Sixteen of these cases had been misdiagnosed pathologically. While the most frequent radiographic finding was a round or ovoid lobulated peripheral mass, other appearances included thin-walled cavities, poorly defined nonsegmental infiltrates, and mediastinal masses. Fifty percent of the patients in this study have died from their tumor, with a mean survival of 15.5 months. This contrasts with both typical carcinoid and small cell undifferentiated carcinoma, in which patients develop fatal metastatic disease in 5% and nearly 100%, respectively. Proper categorization of typical carcinoid, atypical carcinoid, and small cell undifferen- hated carcinoma is necessary to determine appropriate therapy, prognosis, and report- ing of end results. The radiologic features of typical bronchopulmonary carcinoid (TC) and small cell undifferentiated carcinoma of the lung (SCUL) are well known to radiologists. Less well known, however, are the radiologic and clinical features of a related neoplasm, atypical carcinoid (AC). These three neoplasms exhibit neuroendocnne differentia- tion and have a spectrum of microscopic pleomorphism and clinical behavior, with AC being intermediate between the histologically bland, clinically indolent TC and the highly anaplastic, clinically aggressive SCUL. The histologic appearance of AC is somewhat varied, making differentiation of low-grade AC from TC or high-grade AC from SCUL difficult. The clinical and pathologic features of bronchopulmonary AC have been de- scribed, but no comprehensive report of its radiographic appearance exists [1-4]. We reviewed the clinical records and radiographs of 32 patients with this diagnosis in order to assess the range of findings which may result from this tumor. Materials and Methods Twenty-seven cases were identified by review of the pathology files and tumor registries at the medical centers of the University of Virginia and Wake Forest University using similar procedures at both institutions. The years for which the tumor registries were polled included 1970-1981 at UVa and 1974-1984 at WFU. An initial listing of patients with neoplasms that could be histologically mistaken for AC was obtained. These diagnoses included bronchial adenoma, carcinoid, oat cell carcinoma, small cell carcinoma, anaplastic carcinoma, undiffer- entiated carcinoma, and any type of poorly differentiated carcinoma. This listing included 1901 patients. Cases that had had the diagnosis made by small biopsies (<3 mm in greatest dimension), cytology alone, or unavailable outside slides were then eliminated. Slides from the remaining 533 cases were then reviewed by the pathologists to arrive at the 27 cases of AC within these two files. Five cases of AC were obtained from consultations sent by outside Downloaded from www.ajronline.org by 34.228.24.229 on 06/08/20 from IP address 34.228.24.229. Copyright ARRS. For personal use only; all rights reserved