Diagnostic reevaluation of 17 cases of pheochromocytoma - a retrospective study

A rare neuroendocrine tumor, the pheochromocytoma (PCC) raises problems due both the limited experience of the researchers in this field and its pathogenic mechanisms, still not fully elucidated. The malignant potential of this tumor cannot be predicted based on its macro- or microscopic aspects, but on the presence of metastases. The aims of this study were: (1) the reevaluation of data for a pertinent and complete tumor diagnostic and prognostic pattern; (2) the statistical correlation of all investigated parameters with the malignant form and the survival rate in order to obtain a possible predictor of malignancy; (3) the potential identification of initially diagnosed benign tumors that become malignant in time. The retrospective study was conducted on 17 patients diagnosed with pheochromocytoma. We investigated: the personal data, the associated neuroendocrine syndromes, the clinical, the laboratory, the macro- and microscopic data [location, size, Hematoxylin-Eosin (HE) pheochromocytoma of the adrenal gland scaled score (PASS score), and immunohistochemical aspects] and the survival rate (analyzed by Kaplan-Meier method and Log-Rank test). The influence of diagnostic parameters on malignancy was calculated taking into consideration the survival rate. By reevaluation of the 17 cases, we tried to emphasize the value of a complex diagnosis pattern for PCCs, based on the correlation between clinical data, laboratory findings and microscopic features. A significant statistical difference between benign and malignant forms was not registered, but there were parameters as age, association with neuroendocrine syndromes, PASS score and specifically Ki-67 mitotic index that had a powerful impact on the survival rate and could be consider as possible predictors of malignancy. The potential of PCC malignant transformation was revealed in our study, by two cases that have metastasized in time.