IMMUNOHISTOLOGIC ANALYSIS OF GASTROINTESTINAL AND PULMONARY CARCINOID-TUMORS

Carcinoid tumors are potentially malignant neoplasms that arise in var ious body sites, including the lung and gastrointestinal tract. Those that appear cytologically atypical are more likely to behave aggressiv ely than more typical carcinoid tumors. However, in the absence of cyt ological atypia or large tumor size, it is difficult to predict the bi ology of an individual tumor, because some lesions metastasize, wherea s others do not. This study had four aims: (I) To study the expression pattern of p53, Ki-67, NCAM, and S-100 in carcinoid tumors and to rel ate these expression patterns to classical histopathologic features an d to tumor location. (2) To identify nonhistological markers that migh t more accurately predict the early behavior of carcinoid tumors. (3) To determine whether sustentacular cells are present in carcinoid tumo rs arising in tissues derived from different embryological derivatives . (4) To determine the synaptophysin and chromogranin immunoreactivity in neuroendocrine tumors arising in various locations. The immunostai ning reactions were quantitatively scored by three observers. Only 3 o f the 39 tumors (all histologically atypical) were strongly positive f or Ki-67; two of these ic ere also strongly p53 immunoreactive. NCAM i mmunostaining differed according to the site of origin: 76.5% of foreg ut lesions, 58% of the midgut lesions, and 20% of hindgut lesions were positive. S-100 immunostaining ranged from 41% in foregut lesions to 50% in both die hindgut- and midgut-derived tumors. S-100-positive sus tentacular cells were present in 20.5% of carcinoid tumors. All tumors stained with antibodies against synaptophysin. In contrast, 100% of m idgut, 60% of hindgut, and 88% of foregut tumors were chromogranin pos itive. Carcinoid tumors tend to have low proliferative rates. p53 immu nostaining tends to be strongly positive in turners that are histologi cally atypical, but it is negative in typical carcinoid tumors arising in the gastrointestinal tract and lungs. Immunostaining reactions wit h antibodies to NCAM, S-100, and chromogranin differ depending on the site of origin. Synaptophysin stains 100% of carcinoid tumors regardle ss of their site of origin. an contrast, antibodies to chromogranin fa il to stain 40% of hindgut tumors and 12% of foregut carcinoid tumors. S-100-positive sustentacular cells are present in foregut and midgut tumors but not in hindgut tumors. Copyright (C) 1998 by W.B. Saunders Company.