Aggressive Malignant Paraganglioma Involving the Pancreas and Vertebral Column.

ABSTRACT

Paraganglioma (PGL) is a rare neuroendocrine tumor arising from chromaffin cells outside the adrenal medulla. The most common sites are the abdomen and head and neck. Seventy percent (70%) of PGLs are sporadic, and 30% are hereditary; the latter are more often aggressive and malignant and occur in young adults. We report a case of a 36-year-old woman with a history of hypertension and abdominal pheochromocytoma resected at the age of 10 years who presented with back pain. Magnetic resonance imaging of the spine showed vertebral metastasis at L2-L5. Computed tomography of the abdomen showed a mass in the body of the pancreas and a laparoscopic biopsy was performed. The tumor cells had granular eosinophilic/basophilic cytoplasm and showed a nested pattern (Zellballen) with a prominent vascular network and infiltration of dense fibrous connective tissue. Strong and diffuse expression of synaptophysin in tumor cells, S100 expression in sustentacular cells at the periphery of nests, and lack of pancytokeratin expression supported the diagnosis of PGL. Due to limited tissue, it was difficult to determine metastatic vs primary neoplasm of the pancreas. The earlier age of onset and history of abdominal pheochromocytoma suggested the possibility of hereditary PGL associated with succinate dehydrogenase (SDH) deficiency. The tumor cells lacked SDHB expression. Germline mutation testing for SDH was recommended. The patient underwent palliative radiotherapy and systemic chemotherapy. Most PGLs are benign and asymptomatic, but there is an increased risk of cardiovascular mortality secondary to catecholamine secretion, and surgical excision is curative. Malignant PGLs are rare (10-40%), have poor prognosis, and are incurable. Increased size of the tumor, deep tissue infiltration, and high proliferative index increase the risk of malignancy, but metastasis is required for the diagnosis of malignant PGL. The advanced disease is treated with surgical removal of the tumor and combined radiotherapy and chemotherapy.