ISLET-CELL TUMORS OF THE PANCREAS - PATHOLOGICAL-IMAGING CORRELATION AMONG SIZE, NECROSIS AND CYSTS, CALCIFICATION, MALIGNANT BEHAVIOR, ANDFUNCTIONAL STATUS

OBJECTIVE. The purpose of our study was to correlate the imaging and p athologic features of islet cell tumors with regard to tumor size, nec rosis and cysts, calcification, malignant behavior, and functional sta tus. MATERIALS AND METHODS. We retrospectively reviewed the clinical, pathologic, and imaging features of all 133 cases of pathologically pr oved islet cell tumors of the pancreas seen at the Armed Forces instit ute of Pathology, Clinical data, including the patients' symptoms and serologic characteristics, were used to distinguish hyperfunctioning t umors (those causing symptoms related to elevated serum polypeptide le vels) from nonhyper-functioning tumors; hyperfunctioning tumors were d ivided further into insulin-producing and non-insulin-producing types. All patients had at least one cross-sectional imaging study, includin g CT (n = 118), sonography (n = 42), or MR imaging (n = 22). Clinical, pathologic, and imaging features were evaluated and correlated with t umor size, necrosis and cysts, calcification, local invasion, vascular invasion, metastases, and functional status. RESULTS. Islet cell tumo rs with areas of necrosis or cystic change found pathologically and on imaging studies (56/133) were larger (8.4 cm in mean transverse diame ter) than homogeneous solid lesions (2.9 cm in mean transverse diamete r) and were predominantly non-insulin producing (48/56) and nonhyperfu nctioning (36/56). Of the 43 insulinomas, 35 were small (2.2 cm in mea n transverse diameter), solid, and homo-geneous. Larger size also was associated with calcification and malignant behavior, including local invasion, vascular invasion, and distant metastases. CONCLUSION. Our f indings show that cystic and necrotic islet cell tumors are usually no n-insulin-producing and nonhyperfunctioning neoplasms and larger than the typically solid and small insulinomas. Calcification, local invasi on, vascular invasion, and metastatic disease are more commonly seen w ith larger neoplasms.