Mandibular metastasis presenting as the initial maifestation of malignant pheochromocytoma.

A case of 59-year-old male patient presenting with metastasis to the mandible from malignant pheochromocytoma is described. The conventional radiographs and CT images suggested that the lesion was malignant osteogenic tumors or metastatic tumors due to the existence of calcification and widespread periosteal sunburst spiculation. On MRI, an expansive mass was clearly depicted and the signal intensities of the lesion were low to intermediate on T1 weighted image with intermediate to high signal intensity on T2 weighted image. A strong enhancement of the lesion was also observed on contrast enhanced T1 weighted image. On maximum intensity projection image in the arterial phase, the mass showed exceedingly early enhancement and excessively dislocated adjacent vessels. The diagnosis of a pheochromcytoma was difficult on the basis of these imagings. The final diagnosis was based on a biopsy of the mandible and I-131 Meta-iodobenzylguanidine scintigraphy (MIBG) scintigraphy. A primary lesion of the right adrenal showed low uptake due to wide centric necrosis and metastatic lesions of liver, lumber vertebrae, ribs and sacroiliac joint showed high uptake on the I-131 MIBG scintigraphy. The final diagnosis was nonfunctioning malignant pheochromocytoma due to the absence of elevation of catecholamine or its metabolite.