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Endocrine

Endocrine/Head & Neck Parallel Session

39: SDHB-associated Pheochromocytomas: What is their clinical behavior?

Thursday, March 21, 2024
11:27am – 11:37am ET
Location: C102
Disclosure(s):
Thomas Szabo Yamashita, MD: No financial relationships to disclose
Elizabeth G. Grubbs, MD: Cook, Eisai, BSci, Exelixis: Contracted Research (Ongoing); Eli Lilly: Contracted Research (Ongoing)
Introduction: Mutations in succinate dehydrogenase subunit B (SDHB) cause hereditary paraganglioma/pheochromocytoma syndrome type 4 (PGL-4). SDHB-associated pheochromocytomas (PCC) are thought to be rare. Little data exists about the clinical behavior of
SDHB-associated PCC.


Methods: Retrospective review of patients treated(1993-2023) at a tertiary care center for SDHB-associated PCC. Clinical and demographic variables were retrieved to characterize disease-free survival, disease progression and mortality.


Results: 90 SDHB-carriers were identified, 16 presented PCC (18%). Median age at diagnosis of PCC was 40 (range 9-76), 50% of patients were male, 25%(n=4) had distant metastasis (DM) at diagnosis, and 13%(n=2) had synchronous PGL. No patients had bilateral disease. 75% were symptomatic, most commonly hypertension (50%) and catecholaminergic crisis (13%).  94% of patients underwent surgery as initial treatment, curative intent in 75%. 64% underwent open resection. 46% of patients presented T1 disease at diagnosis (range 3-12cm), 20% N1 and 25% M1. Recurrence occurred in 62% of patients undergoing surgery with curative intent (n=8), 75% in MIS vs 67% open, p=0.63. 81% of patients presented disease progression. Bone was the most common site of DM (100%, n=13).  69% had MIBG imaging, 91% positive. Median time from initial surgery until recurrence was 36 months (range 1-295).  Radiation therapy was the most common adjuvant treatment (44%), followed by Iobenguane I-131 (31%). Tyrosine kinase inhibitors and chemotherapy were the most common form of systemic therapy, 31%. Median follow-up time was 56 months (range 1-408 months).  44% of patients were alive, 19% of patients were disease-free and 50% of the patients with DM had stable disease at last follow-up.


Conclusions: 18% of Germline
SDHB mutation-carriers presented with PCC in our series, all unilateral in our series. SDHB-associated PCC was associated with more advanced and recalcitrant disease, and is often MIBG positive. More studies are needed to better understand the clinical behavior of PCC in PGL-4.     

Learning Objectives:

  • Participant will be able to better understand the clinical impact of the clinical differences of SDHB-associated Pheochromocytomas.
  • Upon completion, participants will understand that SDHB-associated are more aggressive and have recalcitrant, unilateral disease.
  • Upon completion, participants will understand that SDHB-associated are often MIBG-positive.