Endocrine Abstracts

Introduction: Pheochromocytomas are rare neuroendocrine tumors whose malignancy is defined by the presence of metastases that may appear several years later. The appropriate follow-up time remains uncertain.

Clinical Case: We present the case of a woman with a history of pheochromocytoma who underwent complete resection at 48 years old. The genetic evaluation was negative for mutations on RET, VHL, SDHB or SDHD genes. At 66 years old, a thoracic vertebral metastasis appeared on MIBG-I123 scintigraphy. The biopsy of the lesion was consistent with neuroendocrine tumor metastasis. The patient was submitted to radiotherapy, radioisotope therapy and kyphoplasty. The radioisotope therapy with MIBG-I123 proved to be ineffective. Therapy with an antagonist of the alpha-adrenergic receptors (phenoxybenzamine) was initiated. In the next eleven years, the MIBG-I123 scans and lombar CT showed progression of bone metastases and doubt about the possibility of liver lesions. Over these years, plasma metanephrine and 3-methoxytyramine remained normal but normetanephrine showed marginal and progressive elevations. At 77 years, the patient underwent a second radioisotope treatment with MIBG-I123, once again ineffective. 3 months later, the patient was admitted with fatigue, respiratory failure and gait imbalance. Chest CT showed miliary pulmonary spread. Bronchoalveolar lavage immunocytochemistry was compatible with NET metastases. 18F-DOPA PET/CT confirmed pulmonary and massive liver metastases and new bone lesions. Cranial CT scan showed cerebellar, lenticular, frontal and hypothalamic–pituitary involvement suggestive of secondary lesions. Despite the pituitary involvement, there was no hormonal deficiency. Plasma normetanephrine increased. The clinical condition worsened and the patient ended up dying 2 months later.

Conclusions: Metastases typically involve bone, liver and lung – cerebral metastases are rare. MIBG-I123 scintigraphy can detect metastases susceptible to radioisotope therapy, but about a third of patients do not respond. Even in the absence of obvious high-risk characteristics, malignancy can occur and it is not easy to predict. This case illustrates the importance of life-long follow-up in these tumors and the unpredictability of occurrence of metastatic lesions.