Expression of the Pituitary Tumor Transforming Gene (PTTG1) in Pheochromocytoma as a Potential Marker for Distinguishing Benign Versus Malignant Tumors

The Distinction between malignant and benign pheochromocytoma has always been a diagnostic challenge over the last decades. To date, the only reliable criterion is metastasis. The aim of the present study was to investigate the possible expression of pituitary-tumor transforming gene (PTTG1) and retinoblastoma (Rb) in benign and malignant pheochromocytoma. Paraffin blocks of 44 and 11 patients diagnosed with benign and malignant pheochromocytoma were collected. Parameters such as sex, age, tumor size, necrosis, and histological features were compared between the benign and malignant groups as well as immunohistochemical labeling using specific antibodies. PTTG1 showed negative expression in all (44) benign and 9 out of 11 (81.8%) malignant tumors with only 2 out of 11 (18.2%) malignant tumors showed positive reactivity for PTTG1 (P: 0.037) with spindle cell histological pattern in both of them (P: 0.013). Although Rb expression in malignant tumors (81.8%) was slightly more than the benign ones (52.3%), no statistically significant correlation was observed (P: 0.087). These results suggest that PTTG1 immunostaining may play a key role in distinguishing between benign and malignant phaeochromocytoma. However, larger studies are necessary to confirm the outcomes of the present study.