Typical and Atypical Pulmonary Carcinoid Tumor... : The American Journal of Surgical Pathology (original) (raw)
Original Article
Typical and Atypical Pulmonary Carcinoid Tumor Overdiagnosed as Small-Cell Carcinoma on Biopsy Specimens
A Major Pitfall in the Management of Lung Cancer Patients
Pelosi, Giuseppe MD*; Rodriguez, Jaime MD†; Viale, Giuseppe MD*; Rosai, Juan MD†
From the *Division of Pathology and Laboratory Medicine, European Institute of Oncology and University of Milan School of Medicine; and †Department of Pathology, National Cancer Institute, Milan, Italy.
Reprints: Giuseppe Pelosi, MD, Divisione di Anatomia Patologica e Medicina di Laboratorio, Istituto Europeo di Oncologia, Via G. Ripamonti, 435, I-20141 Milano, Italy (e-mail: [email protected]).
Abstract
Seven patients with typical or atypical pulmonary carcinoid tumors overdiagnosed as small-cell carcinoma on bronchoscopic biopsies are described. Bronchial biopsies from 9 consecutive small-cell lung carcinoma patients were used as control group for histologic and immunohistochemical studies (cytokeratins, chromogranin A, synaptophysin, Ki-67 [MIB-1], and TTF-1). The carcinoid tumors presented as either central or peripheral lesions composed of tumor cells with granular, sometimes coarse chromatin pattern, high levels of chromogranin A/synaptophysin immunoreactivity, and low (<20%) Ki-67 (MIB-1) labeling index. The tumor stroma contained thin-walled blood vessels. Small-cell carcinomas always showed central tumor location, finely dispersed nuclear chromatin, lower levels of chromogranin A/synaptophysin, and high (>50%) Ki-67 (MIB-1) labeling index. The stroma contained thick-walled blood vessels with glomeruloid configuration. Judging from this study, overdiagnosis of carcinoid tumor as small-cell carcinoma in small crushed bronchial biopsies remains a significant potential problem in a worldwide sample of hospital settings. Careful evaluation of hematoxylin and eosin sections remains the most important tool for the differential diagnosis, with evaluation of tumor cell proliferation by Ki-67 (MIB-1) labeling index emerging from our review as the most useful ancillary technique for the distinction.
© 2005 Lippincott Williams & Wilkins, Inc.