Immunoexpression of villin in neuroendocrine tumors and its diagnostic implications.
BACKGROUND
Villin, a 95-kd cytoskeletal protein associated with axial microfilament bundles of brush border microvilli, is mostly restricted to intestinal glandular tumors. Villin immunoexpression was recently observed in a small number of carcinoids of the intestinal tract and lung, but its significance in a broad category of neuroendocrine tumors has not been evaluated.


METHODS
A total of 114 neuroendocrine tumors of different origins were tested for villin expression. They included gastrointestinal carcinoids (n = 30), lung carcinoids (n = 15), small cell carcinomas of the lung (n = 24), small cell carcinomas of other sites (n = 15), islet cell tumors (n = 8), Merkel cell carcinomas (n = 6), paragangliomas (n = 6), and others (n = 10). Nine round cell sarcomas were tested as well.


RESULTS
Villin immunoreactivity was present in 85% of gastrointestinal carcinoids and small cell carcinomas, but was found in only 40% of lung carcinoids. Other tumors tested were virtually negative for villin. In general, while cytoplasmic reactivity was most common, a characteristic apical membranous pattern simulating brush border was seen in 76% of the gastrointestinal carcinoids and in 50% of the lung carcinoids.


CONCLUSIONS
We found that villin was predominantly restricted to gastrointestinal neuroendocrine tumors (excluding islet cell tumors), although a small number of bronchial carcinoids may be positive as well. These results suggest a role for villin in the differential diagnosis of neuroendocrine tumors.
Zhang
P J
PJ
Department of Pathology and Laboratory Medicine, Roswell Park Cancer Institute, Buffalo, NY, USA.
Harris
K R
KR
Alobeid
B
B
Brooks
J J
JJ
D007516:Adenoma, Islet Cell / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000096:biosynthesis; D002276:Carcinoid Tumor / Q000378:metabolism; D015266:Carcinoma, Merkel Cell / Q000378:metabolism; D018288:Carcinoma, Small Cell / Q000378:metabolism; D002352:Carrier Proteins / Q000096:biosynthesis*; D005770:Gastrointestinal Neoplasms / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000378:metabolism; D008840:Microfilament Proteins / Q000096:biosynthesis*; D018358:Neuroendocrine Tumors / Q000378:metabolism*; D010235:Paraganglioma / Q000378:metabolism; D011237:Predictive Value of Tests; D018228:Sarcoma, Small Cell / Q000378:metabolism
D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D008840:Microfilament Proteins; C026615:villin