MON-393 Neuroblastoma Masquerading as Pheochromocytoma

Abstract

Peripheral neuroblastic tumors (PNTs) are a group of tumors arising from sympathetic ganglion cells. It is a malignancy of childhood and rare in adults. The incidence in adulthood is only 0.12-0.2 cases per million per year. A 37 year old male presented with acute exacerbation of low back pain which started months prior to admission. MRI of the lumbar spine revealed a 3.6 x 3.4 cm lobulated heterogeneous mass-like lesion involving his right adrenal gland therefore, endocrinology evaluation was requested but not completed. He was a non-smoker without any significant past medical or surgical history and was not on any medications. On examination, He was normotensive and appeared to be in moderate distress. He had tenderness over the right sacroiliac joint. His renal and liver functions were normal. Serum metanephrines were normal however, normetanephrines were elevated to 501 pg/mL (< or = 148 pg/mL). Urine normetanephrines were 3,192 ug/day (88-444 ug/d), Urine volume of 3 L, total metanephrines of 3,342 ug/d (140-785 ug/d). Chromogranin A was 1,379 ng/mL (0-95 ng/mL). DHEAS, 17- hydroxyprogesterone, androstendione, and ACTH were normal. CT of his abdomen and pelvis with contrast showed a lobular heterogeneous mass involving the right adrenal gland with an increased size of 4.9 x 4.3 cm measuring 55 Hounsfield Units (HU). Right iliac core needle biopsy was done to evaluate his diffuse osseous metastasis which showed crush artifact, with positive chromogranin and synaptophysin staining. Right posterior pelvic crest lesion excision biopsy showed primitive small round cell neoplasm with neuroendocrine features, favoring an adult type neuroblastoma confirmed by immunohistochemical staining. He received chemotherapy and radiation and prior to debulking surgery, we initiated doxazosin. Surgery revealed a 6 cm neuroblastoma with extraadrenal extension. Iodine 123-metaiodobenzylguanidine (I-123 MIBG) showed extensive diffuse osseous metastatic disease. His catecholamines declined after surgery. Bone marrow (BM) involvement was noted and he underwent bone marrow transplantation with clinical improvement six months post-transplant. Although pediatric neurblastoma has a 91% survival rate, rates progressively decline to 40% in adults aged 25-64 years. Metastatic dissemination occurs in up to 40% of adults, mainly in the bone and BM as seen in our case therefore, adults should have a BM assessment upon diagnosis. Main issue is differentiation between PNTs and pheochromocytoma, that might be challenging due to variable imaging characteristics of PNTs and secretion of catecholamines in up to 70% of PNTs. On the other hand, catecholamines can be used as tumor markers for monitoring. Majority of adult PNTs are high-risk tumors with poor prognosis. No guidelines for adult management exists due to the rarity of the disease.