Endocrine Abstracts

Malignant paraganglioma causing skull metastasis is rare. We describe a 49-year-old male who gives a history of a mass on the vertex of the scalp, noticed a year before presentation and which grew rapidly from 1 cm to 5 cm. His past medical history is significant for hypertension (treated with Amlodipine), and back pain and headache on a regular basis. On MRI the mass measured 5.7 cm craniocaudal, by 7 cm AP and 6.9 cm transverse. Additionally, multiple additional focal areas of bony abnormality (skull base, mandible and upper cervical spine) were present. Multiple myeloma screen was negative, but bone marrow aspirate revealed likely paraganglioma. A CT trunk showed multiple metastasis to ribs and a destructing metastasis to T9 vertebrae as well as a soft tissue mass in the left hemi-pelvis measuring 6.3 cm by 4.2 cm. A PET-CT scan showed extensive uptake in bone and soft tissue disease including lesions within the liver and possible infiltration around the kidneys. Plasma metanephrines were significantly raised: normetanephrine was 47538 pmol/l (<1180) and plasma 3-methoxytyramine measured 675 pmol/l (<180). A rib biopsy result was consistent with bone marrow infiltration by metastatic paraganglioma and Ki67 of 13.1%. The diagnosis of malignant paraganglioma with diffuse metastases was concluded and he was treated with radiotherapy for T9 vertebrae for impending cord compression and also started on Phenoxybenzamine and Propranolol as alpha and beta blockade respectively. He was started on Temozolomide and is being considered for PRRT. Repeat PET-CT showed decreased FDG uptake in previously described bone lesions. Genetic analysis confirms mutation of SDHB gene. This case shows the importance of considering malignant paraganglioma or phaeochromocytoma as a differential diagnosis of bone metastasis including skull, as well as measuring plasma metanephrines before considering biopsy of suspicious soft tissue masses.