OBJECTIVETo evaluate the CT and MR findings of retroperitoneal ectopic pheochromocytoma.

METHODSTo analyze retrospectively the CT and MR images of 32 patients with retroperitoneal ectopic pheochromocytoma proved by pathology.

RESULTSThe lesions (benign=28, malignant=4) were located in the anterior pararenal space (ARS) (n=12), the perirenal space (PS) (n=13) and the posterior pararenal space (PRS) (n=7). The tumors showed heterogeneous density on unenhanced CT (n=25). Among the 23 cases with enhanced CT imaging, 19 cases had marked contrast and 4 had mild contrast. The enhancement patterns included whole enhancement (n=9), solid area enhancement (n=12), peripheral enhancement (n=1), and spotted enhancement (n=1). The tumors had heterogeneous signal on unenhanced MR (n=23), and usually showed enhancement at arterial, portal and delayed phases on 22 enhanced MR, while cystic area with no enhancement. The lesions usually had cystic changes (n=18), septa (n=16), vessels inside (n=9), hemorrhage (n=3), and calcification (n=3). Besides that the morphology had statistical significance (P=0.013), other indexes had no statistical significance (P>0.05) in differential diagnosis of benign and malignant retroperitoneal ectopic pheochromocytomas.

CONCLUSIONSRetroperitoneal ectopic pheochromocytomas have some CT and MR features, usually revealed as an oval mass, growing along the paravertebral axis, and often with cystic changes. Those signs combined with hypertension and elevated catecholamine level may lead to a correct diagnosis.

Adrenal Gland Neoplasms ; diagnostic imaging ; pathology ; Calcinosis ; Diagnosis, Differential ; Humans ; Hypertension ; Image Enhancement ; Pheochromocytoma ; diagnostic imaging ; pathology ; Retroperitoneal Space ; Retrospective Studies ; Tomography, X-Ray Computed

BACKGROUNDBenign and malignant primary retroperitoneal tumors (RT) have different pathological manifestations, and overlapping imaging characteristics. This study aimed to evaluate the value of computed tomography (CT) for differentiating benign from malignant RT.

METHODSOne hundred and ninety-four patients with clinical and radiographic data were evaluated retrospectively following surgical resection of primary RT. There were 38.1% (n = 74) benign lesions and 61.9% (n = 120) malignant lesions. Categorical variables were tested with a chi-square test or Fisher's exact test for the diagnostic indexes and sensitivity and specificity of CT characteristics.

RESULTSIn univariate analysis, the differences in ill-defined margins, irregular surfaces, long diameter >6.75 cm, short diameter >6.25 cm, and solid or mixed texture had statistical significance; the sensitivity and specificity were 44.2% and 91.9%, 70.0% and 62.2%, 68.8% and 60.7%, 59.7% and 74.2%, 87.5% and 35.1%, respectively. In multivariate analysis, a combination of all the above indexes was the best model for differentiating malignant tumors, resulting in the most accurate diagnosis of malignancies with a sensitivity of 77.2% and a specificity of 81.1% (P < 0.0001) when the score was 4. The differences in other findings including CT attenuation, number, and calcification had no statistical significance. The unique characteristics included the spotted enhancement (mottled high density) in schwannoma (P < 0.0001), adipose tissue in liposarcoma (P < 0.0001) and paravertebral location in neurogenic tumors (P < 0.0001).

CONCLUSIONSMore accurate differential diagnosis of primary RT can be made through comprehensive analysis of the combined diagnostic indexes of CT. Some specific characteristics of CT can assist in preoperative planning.

Adolescent ; Adult ; Aged ; Aged, 80 and over ; Child ; Female ; Humans ; Male ; Middle Aged ; Retroperitoneal Neoplasms ; diagnosis ; diagnostic imaging ; Retrospective Studies ; Sensitivity and Specificity ; Tomography, X-Ray Computed ; methods ; Young Adult