SAT-312 A Rare Case of Metastatic Paraganglioma with Positive SDHB Mutation: An Incidentally Found Silent Monster

Introduction: Although paragangliomas (PG) are derived from extra-adrenal chromaffin cells of sympathetic paravertebral ganglia in the thorax, abdomen, and pelvis, they can also arise from parasympathetic ganglia located along the glossopharyngeal and vagal nerves in the neck and at the base of the skull. Non-secretory PG have a low prevalence, are often silent, and can present as a malignant tumor with mass effects. Symptoms often include: unilateral hearing loss, pulsatile tinnitus, cough, hoarseness, pharyngeal fullness, swallowing difficulty, pain, and/or problems with tongue motion. Case: A 25 year old African American woman presented with 2 yrs of exertional presyncope, night sweats, subjective fevers, 20 lb. weight loss and a nontender enlarging left neck mass. Family history: Mother had thyroid cancer. Physical exam- BMI 21 kg/m2, BP 118/72 mmHg, HR 74, with indurated, fixed, nontender mass in left upper neck, inferior to mandibular angle. Laboratory-Hgb 6.9 g/dl, MCV 71.7, Iron 137 mcg/dl, TIBC 151 mcg/dl, Ferritin 155 ng/ml, CRP 65.20 mg/dl, ESR 122 mm/hr, AST 107 U/l, ALT 7 U/L, Alk Phos 81 U/l. EGD and Colonoscopy-normal. CT scan of neck, abdomen and pelvis: 6.0x3.5x2.7 cm heterogeneously enhancing mass in left neck involving skull base at carotid canal level, within the internal carotid space, causing external compression of left internal jugular vein, with multiple hypervascular lesions in bilateral lungs, liver and spleen, as well as cervical, thoracic, lumbar and sacral spine. Packed red blood cells were transfused. Liver Biopsy-metastatic paraganglioma with SDHB mutation. Laboratory tests- normal plasma catecholamines, thyroid function tests, prolactin, cortisol, ACTH, LH, FSH. A few weeks later, she reported new onset left sided tinnitus, orbital pain and vision changes. MRI Brain/orbit- 10 x 11 mm enhancing lesion centered in left cavernous sinus near orbital apex without intra or extraconal lesion. Chemotherapy was started with vincristine, cyclophosphamide and dacarbazine. After 12 weeks of chemotherapy, the left neck mass size decreased, tinnitus, and vision changes resolved. She was referred for genetic counseling and multidisciplinary care. Discussion: Our patient had malignant head and neck PG with SDHB mutation. Mutations in the gene encoding SDH subunit B (SDHB) can lead to metastatic disease in ≥ 40% of patients, are frequently familial, and are associated with other malignancies (renal cell carcinoma, pituitary adenoma, breast and thyroid cancer). Although there are current guidelines regarding diagnosis and management of non-malignant secretory paraganglioma/pheochromocytoma, screening and management of metastatic disease is not clear. Therefore, it is important to have a low threshold of suspicion for early diagnosis. Provider awareness and education regarding diagnosis and management is needed.